Archive of Our Own

Enormous yet silent, Theia hurtles through a solar system at seventy kilometers per second. This planet formed at the outer edges of the solar system billions of years ago, yet within an hour it will cease to exist. By random chance, Theia is on a perfect trajectory to collide with the solar system’s third planet from the sun.

Most of Theia’s residents have accepted the apocalypse: the end of their existence. Clustered communities have existed peacefully for thousands of generations, so it makes sense that they all shall perish together, too.

However, not everyone accepts the inevitable. A handful of Theia’s residents are not ready to die yet.

Three microscopic organisms gather deep below the planet’s rocky surface. Far away from the sunlight they depend on to survive, these tiny organisms are weak and weary, but this was the only place where they could go. In this one little spot, sheltered beneath Theia’s landscape, they might be able to survive.

Hiding in the darkness of a cave, the three organisms layer themselves on top of each other: Dream, George, and Sapnap. With only minutes left until the apocalypse, the companions overlap for a final goodbye in case they do not outlast the collision.

Even without voices and words, the three companions reach a mutual understanding of how much they will miss each other. They are afraid, full of dread and hope. If they become separated somehow, they would like to find each other again… but would that really be possible? How could three microscopic organisms without mouths, eyes, or ears possibly find each other again after their planet is obliterated?

Entering its counterpart’s gravitational field, Theia smashes into the solar system’s third planet. Unlike asteroids, which crack and rupture upon collision, these two planets fuse. Friction melts solid rock into molten lava, causing the cores of Theia and its counterpart to meld together.

Tremors shake Theia’s surface, rippling through the planet. Dream, George, and Sapnap cling to each other instinctively as deafening rumbles fill the cavern around them. Shock waves reverberate through Theia, collapsing its cave systems. Waves of sweltering heat overwhelm the cavern’s dense, heavy air. Theia’s collision with the other planet annihilates everything on its surface, including all of its microscopic communities. In a fraction of a second, Dream, George, and Sapnap become the sole survivors of their species.

Searing winds rip Dream, George, and Sapnap apart. They must cling to dust particles instead while air currents throw them high into the fused planet’s atmosphere.

Meanwhile temperatures on the surface soar to 3,000 degrees Celsius. Debris explodes out as Theia and its counterpart fuse together into one singular planet. Their cores combine, sending enormous shockwaves throughout both balls of infernal rock.

High in the stratosphere beside the border with space, forceful winds blow the three terrified microorganisms further apart. Unable to sense each other nearby anymore, Dream, George, and Sapnap can only wait helplessly. Each survivor feels completely alone. Not much hope remains, but at least all three are alive despite the immense distance that separates them. They can do nothing except be patient and wait for something to change.

500 million years after the collision, Theia and its counterpart have fully combined into something new: our Earth. Now the third planet from the sun is a mighty inferno of magma and rock. It spins fast on its axis, so each day is only a few hours long. The planet’s heavy metal core is stable, creating an electrical field. Beyond its atmosphere, all of the remaining debris from the collision has formed a cold, lifeless sphere which orbits around Earth: our moon.

While a thin layer of gas settles over the planet's surface, Earth’s gravitational field attracts thousands of small asteroids toward its colossal mass. These asteroids become meteors when they smash into the planet’s surface, adding to its mass further. Water exists only as steam in the air. Volcanoes erupt across the globe, heaving lava and hurling boulders. Their gaping mouths churn out plumes of billowing methane and sulfur.

Without anything else to do, the three microorganisms Dream, George, and Sapnap are dormant, deep in hibernation. They have slept for almost 500 million years by now, unaware that their world actually did not end. Of course there is nowhere for them to go yet, but Theia’s evolution into the modern Earth is done. Soon its last three children will witness an entirely new form of evolution.

A big change has happened. Theia has been gone for one billion years, and now its descendant the Earth is unrecognizable. Some volcanoes still explode, expanding the planet’s continents, but most of the molten rock has cooled and settled. Global temperatures plunged and it spins slower on its axis. Steam in the atmosphere has also formed a blanket of clouds. Water vapor condensed and drifted to the planet’s surface. The world’s first storms dump torrential rains into vast oceans. Waves lap at barren shores, eroding minerals out of the stones.

Dream, George, and Sapnap have finally awoken from their long slumber. No longer confined to the stratosphere, the three lifeforms jolted back into consciousness when their microscopic bodies floated down to touch the sea. Water and sunlight rejuvenate their ancient souls.

Unbelievably Dream, George, and Sapnap are not alone anymore, either. Nothing exists on land yet, and most of the oceans are still empty… but among their depths, new visitors have arrived. Extremely simple cyanobacteria cluster near geothermal vents in underwater canyons. Made of collections of proteins - DNA - these single-celled organisms form dense mats across the ocean floor. Dream, George, and Sapnap are even smaller. In different oceans they latch onto cyanobacteria, anchoring themselves. Soon they discover that these new lifeforms are excellent sources of energy, so they begin feeding on the cyanobacteria’s proteins to nourish their own bodies.

So far the Earth is still desolate. However with some more time, its primitive single-celled residents might become something even better.

Unbeknownst to Dream, George, and Sapnap, the world around them is not the only thing that has undergone significant changes. During their extensive time in the stratosphere, there was almost no ozone to protect them from the sun’s radiation. While they hibernated, the three microorganisms mutated without even realizing the incredible ability they gained. Only after attaching themselves to various forms of cyanobacteria did they realize their own bodies were more than what they remembered.

Dream, George, and Sapnap have become shapeshifters, able to acquire the DNA from any lifeform they touch. They can transform the structures of their own bodies to perfectly replicate anything, whether big or small. This ability is remarkable, but it also has limitations. The shapeshifters cannot simply transform into whatever they want, whenever they want. Instead they can only transform into their most recent acquisition, and they cannot reverse the transformation once it is complete. Every time the shapeshifters change their forms, they rewrite over the same singular save file.

Dream, George, and Sapnap are still far apart from each other, too. Drifting in separate oceans, they remain practically invisible, but they are not as microscopic as they once were. All three organisms have shapeshifted into plankton halfway through a crucial moment of Earth’s history: the Great Oxidation Event.

Until this point, single-celled plants and algae in the oceans have photosynthesized using sulfur for millions of years. Gradually they are evolving to photosynthesize with carbon dioxide instead, a process which results in an unexpected byproduct: oxygen. Billions of tiny plankton flood the oceans with oxygen, and there is so much excess gas that it begins to fill the atmosphere, too.

Oxygen is also toxic to almost all of the other primitive lifeforms which have been developing for the past several hundred million years. Dream, George, and Sapnap witness catastrophic levels of extinction among Earth’s developing residents. Billions of single-celled organisms shrivel and die around them, causing the shapeshifters to become fearful. Have they chosen wrong? Were plankton doomed to fail after all? If Theia’s children perish and descend into the abyss, will they ever escape?

Perhaps the shapeshifters will never reunite… but they cannot know for certain yet. For now all that Dream, George, and Sapnap can do is copy the lifeforms around them and adapt.

The Earth’s continents are no longer stationary like they once were. Huge sheets of solid rock shift around deep below the crust: tectonic plates. Sliding and bumping into each other, they form mountains on land and trenches underwater. As the continents move, ocean currents and weather patterns change alongside them.

Life in the oceans has not remained stagnant, either. Simple single-celled organisms have recovered from the Great Oxidation Event. The oxygen-rich atmosphere thickens, full of ozone that protects the Earth’s surface from the sun’s radiation.

Like the other lifeforms around them, Dream, George, and Sapnap have evolved, too. They are no longer photosynthesizing phytoplankton. Instead they have shapeshifted into predatory zooplankton, capable of engulfing and digesting smaller lifeforms such as algae and bacteria.

The planet’s residents are still developing at a glacial pace, but another unexpected event is on its way to test their resilience.

The new “Snowball Earth” is extremely cold and completely frozen. A thick layer of ice covers both the land and oceans. Organisms which could not adapt fast enough have perished. Almost all life on Earth is in hibernation, including Dream, George, and Sapnap. The trio of survivors are now basic multicellular organisms, but like their neighbors, they have succumbed to a deep slumber. Stronger yet still microscopic, they float in freezing water while continents continue to shift beneath them. Being so tiny in a world so vast, the shapeshifters have still not located their lost companions, but Dream, George, and Sapnap must maintain their hope. Somehow, if they survive the next few million years trapped beneath kilometers of ice, they must find each other again.

By now the planet’s rotation has slowed; each day lasts twenty-one hours. The moon has drifted further from the planet, so its gravitational pull on the tides has lessened.

“Snowball Earth” has also thawed, but the global climate is more mellow than earlier. Whereas the first four billion years were characterized by blazing days and frigid nights, nowadays the temperatures remain relatively stable regardless of the hour. The average day’s temperature is seventeen degrees Celsius, but frozen areas linger on the globe’s northern and southern poles.

Most importantly, the ice sheets which covered most of the planet have melted. All of the organisms which managed to outlast the Cryogenian Period have recovered and reproduced, beginning new lineages of lifeforms who are more adaptable than their predecessors.

Now there are more options for the shapeshifters to acquire. For the first time, Theia’s three survivors adopt forms that are significantly different from each other. Dream is an Auroralumina cnidarian, an ancient ancestor of jellyfish. Sapnap is a Dickinsonia, one of the first known animals to feature bilateral symmetry; both the left and right sides of his body are identical to each other. George is a charnia frond, a plant-like creature without organs or a mouth, absorbing nutrients from the sea around himself.

All three of the shapeshifters are animals now, but their lifestyles are relatively passive and sedentary. However, as evolution speeds up around them, their battle for survival on Earth will soon become much more intense.

An explosion of organisms has diversified, filling the oceans with new creatures which have never been seen before… and indeed they can be seen. Microscopic single-celled organisms are still the most common lifeforms by sheer numbers, but the Earth’s multicellular residents have made the most impressive progress, constantly changing like the world around them.

Animals do not need to live stationary lives anymore. They have evolved eyes and nervous systems, allowing them to analyze their surroundings and react if they sense a potential meal or a potential threat.

Filter-feeding is no longer the most efficient way to find food, so the shapeshifters have adjusted their survival tactics. Dream has transformed into a trilobite, crawling along the ocean floor and scavenging from the corpses of dead creatures. Trilobites are early arthropods related to modern insects, arachnids, and crustaceans. They have compound eyes with hundreds of lenses that each perceive their surroundings from a slightly different angle. They also have tough, segmented exoskeletons to protect themselves from parasites and predators… like Sapnap.

The other shapeshifter is also an arthropod, but he is an Anomalocaris: the Earth’s first apex predator. Sapnap is fifty centimeters long: a giant compared to his prey. He has two compound eyes on stalks, and two maneuverable tentacles in front of his mouth to snatch any creature that cannot escape in time. While Dream uses crab-like legs to scurry along the sand, Sapnap swims using a row of hard flippers on each side of his body.

These two armored arthropods - Anomalocaris and the trilobites - have been locked in an evolutionary arms-race for millions of years. Whenever one of them evolves a new way to kill or to avoid being killed, the other one must adapt or die.

Theia’s third survivor is not involved in this arms-race, however. George has selected an entirely different method of survival. He did not shapeshift into an arthropod at all; instead he chose to be something far more unusual.

George is a Haikouichthys, a creature the size of a human fingernail. He is a scavenger like Dream, but the structure of his body is completely different. Haikouichthys has no external armor; instead it has tiny scales, tiny fins, a skull, and a flexible spine that stretches along the length of its body. George is among the first fish to swim through Earth’s oceans, and he is among the distant ancestors of all fish and vertebrates who will come in the future.

Land is not barren anymore. Earlier in the Paleozoic Era, clusters of coastal sea plants developed tendrils which enabled them to anchor themselves to rocks. These tendrils strengthened and developed into the world's first roots, and each of the sea plants evolved cell walls to prevent loss of moisture during low tide. Absorbing minerals and nutrients from the volcanic stones beneath them, these early pioneers evolved stems and leaves, allowing them to grow upward in search of sunlight. They are not sea plants anymore. They have become gymnosperms: the first wave of terrestrial plants to cover the planet with green. Ferns, cycads, and conifers rule the world, and when they die, they decompose into layers of soil that nourish their descendants.

Whereas plants have conquered the land, animals still dominate the sea. Sponges, urchins, clams, fish, mollusks, crustaceans, and corals form complex food chains, but arthropods are not the apex predators anymore.

When George chose to remain a fish, he chose well. Now he is a two-meter-long Stethacanthus shark, fast and agile. His bone structure has expanded from its primitive beginning as a skull and spine, developing teeth and a powerful tail. Every day he slinks between the sunny and dark parts of the ocean, searching for food… and of course, his missing friends.

Dream is not too far away, actually. He has shapeshifted into one of the Devonian Period’s many species of ammonites: cephalopods with shells. He is much larger than George, with an asymmetrical shell and fleshy tentacles that are several meters long. Unfortunately, because he must hide his soft parts whenever he senses danger, the alarming sight of a Stethacanthus shark nearby causes Dream to withdraw into his shell for safety.

Unaware that this particular ammonite is not like the hundreds of others he has encountered and devoured, George swims past without a second thought.

Today was the closest any of the shapeshifters have come to finding each other in four billion years, but they had no idea.

When Sapnap noticed the rising prominence of vertebrates, he switched from his arthropod form. Back in the Silurian Period before the Devonian, he latched his shrimp-like body to a passing Cephalaspis fish and acquired its DNA. Like its ancestor Haikouichthys, Cephalaspis represented a significant landmark in evolution for vertebrates. Instead of compound eyes, Sapnap grew eyeballs with a singular lens that allowed him to see one picture clearly rather than dozens of fragmented images. Cephalaspis also had a more complex nervous system than its ancestor, with millions of nerve endings that allowed it to detect subtle vibrations in the water around it. In all of its descendants, this ability became the sense of touch.

Of course, by this point, Cephalaspis does not exist anymore. In the Carboniferous Period today, the vertebrates are no longer confined to the sea. Flimsy fins became muscular limbs, and aquatic gills became air-breathing lungs. Sapnap is now an amphibian: a terrestrial creature who retains his loyalty to the water that sustained him for billions of years.

George has moved onto land, too, but he was eager to leave the ocean behind and explore unseen territory. He adopted the form of a reptile: specifically an early lizard which can also trace its ancestry back to the amphibians and fish. Although George has lost his gills, his skin is waterproof, and he has gained a few remarkable skills as well.

Like the other early reptiles, George’s heart rate slows down when he is relaxed and it quickens when he is afraid. Conserving energy like this enables him to outrun arthropod predators like scorpions and spiders, who can only chase their prey for short distances before they run out of energy. Like the sense of touch, an efficient cardiovascular system is another trait that the reptiles and their descendants - sauropsids like birds and synapsids like mammals - will inherit in the future.

Theia’s survivors and Earth’s residents will need all of the advantages that they can get, for the worst disaster in the planet’s history is not far away.

The Paleozoic Era concludes with the most catastrophic mass extinction event that Earth has ever seen. A supervolcano erupts - the Siberian Traps - ejecting massive quantities of methane and carbon dioxide into the atmosphere. At the same time, tectonic plates have caused continents to shift and combine into the supercontinent Pangea: a land mass so enormous that rain clouds cannot reach its center. The majority of Pangea is a searing desert, with all forests restricted to its outer edges.

Global temperatures soar to seventy-four degrees Celsius at the equator, and the oceans warm up to a balmy thirty-seven degrees Celsius. All of the lifeforms that could not adapt to the relentless heat have already died, but even the survivors are struggling.

In this unforgiving environment, the shapeshifters are rapidly losing options for lifeforms to acquire. Currently Dream is a Smilesaurus, a synapsid which is more similar to mammals than to its reptilian ancestors. He is one of the apex predators of the late Permian Period, but this does not mean much when there is not much left to eat.

George is also a synapsid, a closely related Gorgonops, but he cannot find enough food, either.

The only shapeshifter with the right idea was Sapnap. He transformed into a different synapsid, a small burrowing creature called Diictodon. Of course he would prefer to be something more powerful and intimidating, but he knows this form is a smarter choice. Diictodons dig extensive networks of tunnels beneath the desert soil, where the air is cooler and there are plenty of roots to eat.

Over ninety percent of life on Earth will die by the end of the Permian Period, and the shapeshifters hope that they will not be included.

Salvation has come. Earth’s tectonic plates are shifting apart again, allowing rain to penetrate the continents. Deserts shrink and forests expand. Trees extract carbon dioxide from the atmosphere, global temperatures drop, and the sweltering heat ebbs.

When ninety percent of the planet’s organisms perished, they left behind a multitude of ecological niches. All of the survivors and their descendants swiftly diversified to fill these open roles, so the Earth is brimming with life once again.

At the end of the Permian Period, Dream was certain that he had reached his end. He was still a Smilesaurus, but he could not find any living creatures to acquire until the last possible moment. A small reptilian archosaur approached his dehydrated body as Dream clung to consciousness. When the archosaur’s jaws plunged into his abdomen, ripping his flesh apart, Dream seized the opportunity. As the archosaur’s gums touched his skin, he gathered its DNA and beat death itself.

Rejuvenated, the shapeshifter jolted away, transforming into the exact creature who intended to consume him. In the Triassic Period, Dream and several other reptilian archosaurs became crocodiles. They are ambush predators, adapted to a half-terrestrial, half-aquatic lifestyle. Their eyes and nostrils are at the tops of their skulls, allowing them to monitor the river’s edge for a potential meal even while the rest of their bodies are submerged underwater. Crocodiles also have a slow metabolism, able to survive for one year without food.

Dream has learned from his mistakes, and George is trying to learn from his mistakes, too. So far he is succeeding as a Lystrosaurus, the most common terrestrial animal of the Triassic Period. These are synapsids - protomammals like their ancestors the Diictodons - but Lystrosaurus is too large to burrow. Instead they migrate in herds, grazing on plants and traversing the mountainous landscape.

Today the migrating Lystrosaurus herd will cross a river. Hundreds of crocodiles wait beneath churning waters, eager for their annual feast. Dream is among them, patient despite his hunger. As thousands of Lystrosaurus approach from the distant horizon, he anticipates gorging himself on their warm flesh, eating enough to last until next year.

George is among the Lystrosaurus herd, but no one notices the shapeshifter. He looks identical to them, so none of the herbivores startle when one member wanders away from the rest of the herd. Unlike the others, George is much more aware of the danger ahead. He remembers crossing this river last year, and the year before that. He only managed to acquire a Lystrosaurus at all because he was a crocodile feasting upon one.

Therefore George alters his course and plans a different route to the forest on the river’s opposite side. He travels upstream along a more perilous route, but at least he will avoid most of the crocodiles who gather downstream.

Dream and George miss each other again, and neither of them are close to Sapnap either.

The third shapeshifter is stranded far from his companions, for he has returned to the ocean. Sapnap is a Mixosaurus, an ichthyosaur with a long snout and flippers, but he is not a fish. Sapnap is a marine reptile with lungs. Like the sea turtles that are evolving alongside them, marine reptiles only return to the land to lay their eggs.

All three of Theia’s descendants have chosen strong candidates for survival. Crocodiles, Lystrosaurus, and ichthyosaurs are all perfect for the Triassic Period… yet none of them are destined for world domination. Instead the next rulers of the world will be the dinosaurs.

While some archosaurs became crocodiles, others started a new lineage: a clade called Dinosauria. This clade split up at the beginning of the Jurassic Period, forming three groups: the ornithopods, the sauropods, and the theropods. Marine reptiles like ichthyosaurs and flying reptiles like pterosaurs are technically not dinosaurs, but together all of these reptiles hold the most dominant positions in every ecosystem.

George enjoyed the security he felt while existing as one animal camouflaging among a herd of many, so he maintains that strategy today. Now he is a Brachiosaurus, a gigantic herbivorous dinosaur who browses leaves from the treetops. Most sauropods become prey long before they reach this colossal size, but the advantage of being a shapeshifter is that George did not need to dodge predators at all. Instead he simply acquired an adult Brachiosaurus and transformed, brimming with triumph at his easy lifestyle.

Dream’s situation is not so effortless. He took a risk by abandoning his crocodilian morph to adopt a new form: the Microraptor. Unlike the titans who topple trees and crush rocks beneath each step, Dream is an opportunist. He and the other Microraptors gather in trees, flicking their feathered wings, chirping whenever they spot a dinosaur passing below the branches. Next they swoop down, gobbling worms and insects from the bigger dinosaur’s footprints in the soil. Microraptors might not be the most prominent theropods compared to their relatives Deinonychus and Velociraptor, but Dream’s feathers indicate that this creature is another important landmark in evolutionary history.

Birds evolved from dinosaurs, and although they have not diversified yet, the tiny feathered creatures will soon gain a much more prominent role in Earth’s history.

Another disaster is approaching, and unlike the gradual shifts in tectonic plates which caused the Permian Extinction, this catastrophe will be much more sudden.

Enormous yet silent, an asteroid hurtles through space. Originating from the solar system’s outer asteroid belt, it has slipped through an endless black void for years, but soon its journey will reach a cataclysmic end.

When asteroids enter the Earth’s gravitational field and atmosphere, they become meteors. Meteors have visited the planet every day since its formation, but the vast majority are tiny, weighing one kilogram or less. These small meteors - meteorites - usually vaporize within moments or minutes, long before they reach the surface. Winds disperse the resulting dust, distributing it through the air until it settles harmlessly upon the ground.

This meteor is not like the others. It is ten kilometers in diameter - a chunk of rock bigger than Mount Everest - and today it will bring the end of the Mesozoic Era.

During springtime in the northern hemisphere, all three of the shapeshifters occupy the continent which will someday be North America. Although they are hundreds of kilometers apart, the trio will witness the beginning of the end at the same time.

Dream is an Alamosaurus, browsing amongst a grove of conifer trees near the coastline. Although he is not as committed to the sea as Sapnap, he enjoys the pleasant view and the calming sound of waves lapping against the shore. It is the middle of the night, but he is unafraid of the forest’s wildlife. At his maximum size of twenty-six meters long, Dream is a titan: practically untouchable. The sauropod is relaxed, casually shuffling from tree to tree.

Across the continent, George is an Ankylosaurus. He is only seven meters long, not as massive as a sauropod, but he feels equally safe wandering alone at night. Heavy armor made of solid bone covers his entire body. There are even tiny plates of armor shielding his eyelids. At the end of his tail is a club - also made of solid bone - which he uses as a defensive weapon in case any predatory dinosaurs are reckless enough to attack him. Right now he grazes on ferns, absently swinging his tail club from side to side as he chews.

Sapnap also walks alone, but his main weapons are his teeth and jaws. Tyrannosaurus possessed the strongest bite the world has ever seen: 560 kilograms of force per square centimeter. Sapnap is the most terrifying predator of the Cretaceous Period… yet his bulk and strength will be useless to save himself from what is coming.

High above the planet, the meteor breaches the barrier between space and the atmosphere. Sudden friction causes it to burst into flame, burning brighter than the sun. For a brief moment the night becomes day and black skies turn blue, but the meteor’s approach is ominously silent. Traveling at terminal velocity - seventy kilometers per second - the flaming rock plummets faster than the speed of sound.

Less than two seconds after it appeared, blinding all eyes unfortunate enough to notice it, the meteor collides with the earth. It strikes the shallow sea off the coast of what will someday be the Yucatan Peninsula in Mexico. Plunging into the water, it instantly vaporizes the entire sea into a wall of steam. Shock waves ripple outward from the collision site, sending magnitude-11 earthquakes in every direction. Powerful waves of sulfuric ash and superheated air engulf the planet.

The nighttime fills with the yelps and cries of frightened animals as they flee. Most of them are unaware of what happened; they do not even know what they are trying to escape. Tiny mammals dive into their burrows. Birds flutter to hide amongst the trees. Dinosaurs seek shelter in caves or with their herds. For almost all of the creatures on this side of the globe, these are their final moments of life.

Dream was one of the poor animals who caught a glimpse of the meteor before it hit. His vision is gone - burned away - but he remembers the direction of the ocean. Spooked, the sauropod bellows and thunders through the forest until he feels gravel beneath his feet. Following the sound of the waves, he is unaware that he is walking straight toward his doom.

When the magnitude-11 earthquake reaches him, Dream feels the ground shake. Tremors vibrate in his skeleton, and the water abruptly ebbs. Confused, the shapeshifter stumbles on unsteady legs closer to where the water is supposed to be. Plodding feet sink into wet sand and mud. Where has the sea gone?

Ahead is the answer. After the impact and earthquakes are the tsunamis. A wall of water 100 meters tall barrels toward the continent. It hits the sauropod with the force of concrete, crushing him as it sweeps inland. Salty ocean water surrounds Dream’s body before he loses consciousness.

Worldwide tsunamis flatten trees and wipe away landscapes… but perhaps drowning is not the worst fate to suffer. Alongside the shock waves and earthquakes, heat waves from the impact site surge across the world. Global wildfires ignite and explode, covering all of the land that is still above water.

Sapnap must sprint at top speed to outrun the spreading flames. Tyrannosaurus does not fear anything except fire, and the forest around him is blossoming into an inferno. Terrified, he runs, crashing through undergrowth with his eyes focused on the distant mountains ahead. There the ground is unstable and the air will be smoky, but at least he will not burn alive.

George attempts to evade the wildfires, too, but his protective armor has become his ultimate weakness. Heavy plates of solid bone slow him down. His trotting pace is not fast enough to avoid the flames. Embers sear the bottoms of his feet; he groans with agony. Around him, creatures that are smaller or swifter bustle past, leaving the tanky herbivore behind. Predators and prey flee together, united for once in their panicked desperation to survive even when there is nowhere for them to go.

Tsunamis have demolished the coasts, wildfires have consumed the land, earthquakes have ravaged the continents… and this is only the first day of the Cretaceous Extinction.

When the sun rises the next morning, its light cannot even shine upon the carnage. A thick layer of sulfuric ash surrounds the planet, blocking all daylight, but there are barely any plants left on land to photosynthesize anyway. The magnitude-11 earthquakes also disrupted magma deposits beneath the Earth’s crust. Dozens of volcanic eruptions eject molten lava across landscapes which were already destroyed.

Another apocalypse has arrived, and the three shapeshifters will be lucky to survive it.

Dream regained consciousness before he drowned, only to discover that a marine reptile found his body first. Ignoring the disaster happening on land, a Mosasaurus is busy attempting to devour the sauropod. Dream reacts, flinching when serrated teeth plunge into his tail. Forcing himself to concentrate even as he runs out of air, the shapeshifter focuses on the Mosasaurus until he feels the change begin. Acquiring the creature’s DNA, Dream’s body shifts. His mass shrinks, his proportions change, and his bones realign until the marine reptile releases his tail. Surprised, his attacker flicks its flippers to scoot away from the bizarre lifeform that just morphed into itself. Swimming up to the surface, Dream shoves his snout out of the ocean to refill his lungs. Inhaling a huge breath, the new Mosasaurus pulls his head beneath the waves again. Hopefully staying underwater will be safer.

George is in an equally precarious situation. Bleeding from burns between his armor plates, the Ankylosaurus limps through a scorched forest. Smoke emanates from blackened stumps and coal-stained boulders. Of course there is nothing for him to eat, so all he can do is march onward across the desolate landscape… until an enemy blocks his path. A Quetzelcoatlus, the largest flying reptile of the Cretaceous Period, swoops to perch before him. Its long beak and dainty limbs allow it to hop toward the Ankylosaurus with little fear for its own safety. The Quetzalcoatlus has flown above the fires for hours, and now it is ravenous. Squawking at George, the bothersome reptile attempts in vain to flip him over. First the herbivore wonders if he should use his tail club before he gets a better idea. He holds still, allowing the Quetzalcoatlus to poke his flesh with its beak. Just like Dream, the shapeshifter retaliates by transforming into his opponent. Bony armor plates disappear, a tail club shrivels into nothing, and his weight dwindles. Leathery wings unfurl, connecting his front and back limbs like sails of a ship. Startled, the Quetzalcoatlus withdraws its beak, studying George as the shapeshifter becomes a reflection of itself. Suddenly this is a fair fight, so the flying reptile deserts the scene. Opening its wings, it propels itself into the sky to seek an easier target. Squawking in triumph, George copies his defeated opponent. Launching himself off the ground, the shapeshifter soars up from the place that nearly claimed his life. Maybe being a flier instead of a tank will be better.

Sapnap’s situation is different. He is the apex predator of the Cretaceous Period, and like other tyrannosaurs, he finds no shortage of food. Dead dinosaurs litter the landscape wherever he goes. Carcasses of ceratopsids, hadrosaurs, and orthomimids provide an abundance for carnivores… but Sapnap knows this bounty will not last. Soon the bodies will decay and decompose, and the entire food chain will collapse. Determined to prepare for the inevitable, the shapeshifter uses his acute sense of smell to locate something alive. He follows the footprints of a weak, injured dinosaur that is smaller: a Pachycephalosaurus. This creature is not a substantial meal for such an enormous predator, but Sapnap does not intend to eat it. The Tyrannosaurus stalks the Pachycephalosaurus, cornering it against a cliffside. Disoriented from panic and blood loss, the little dinosaur barely notices the thirteen-meter-long monster pursuing it until powerful jaws close around its body. As gently as he can, Sapnap grasps the Pachycephalosaurus, holding it for long enough that its skin can touch his tongue. Opening his mouth, the Tyrannosaurus releases his prey, and then he shapeshifts. He remains bipedal, but his teeth and bulk vanish. Sapnap becomes lithe and agile, with a bony crest that shields his skull. Pachycephalosaurus is not what he wanted to be, but perhaps being smaller is smarter.

Today is the second day of the extinction event, but soon the number of days will not matter anymore. For the next several decades, Earth will be a dark, gloomy world. Perpetually overcast skies prevent phytoplankton and plants from photosynthesizing. Most of them will perish, and losing these foundational lifeforms will erase entire ecosystems. Even after surviving a meteor impact, tsunamis, earthquakes, wildfires, and volcanic eruptions, many animals will end up starving to death anyway.

The future has never seemed so bleak… but life on Earth always finds a way.

One million years after the meteor, Earth is remarkably different. Gymnosperm plants like ferns, cycads, and conifers dominated the Paleozoic and Mesozoic Eras, but their reign has ended. Angiosperm plants have replaced them: newcomers who reproduce with flowers and fruits instead of spores. Angiosperm seeds were superior, able to lay dormant for months or years underground until soil conditions were right for germination. Pollinators like bees and beetles are also evolving to feast on flower nectar, deftly spreading pollen from plant to plant as they feed.

While all of the huge dinosaurs perished within the first few centuries after the meteor impact, plenty of smaller animals managed to outlast the apocalypse. Little furry mammals could burrow, safely eating roots and insects underground. Snakes, tortoises, and lizards relied on the sun to regulate their body temperature, so they needed much less food to sustain their metabolism. Birds became the last representatives of the dinosaurs, surviving on modest diets of seeds and worms.

As the marine reptiles began to starve, Dream left the sea behind again to morph back into a familiar form: a crocodile. When the climate becomes harsh, he can sink into a deep hibernation, conserving his energy until seasonal food becomes plentiful.

All of the flying reptiles died too, but George enjoyed the liberating sensation of flight, so he switched his form to a tiny passerine bird. As a sparrow he perches on branches high above the ground, singing and fluttering from tree to tree.

Although Sapnap yearns for the confidence of a predator, he knows that lifestyle would be too risky. Therefore he has become a rat-like rodent, energetic and dexterous.

Gradually the volcanic eruptions subside. The skies become clear and blue again. Forests and grasslands spread, reclaiming the territory that their ancestors lost until the continents are lush and green again. The age of dinosaurs is over, but new lifeforms are already evolving to take their place.

While birds, arthropods, and reptiles were the first creatures to recover after the Cretaceous Extinction, it was the mammals who eventually conquered the planet. Mammals are endothermic, producing their own body heat, so they do not depend on warm weather to function. Their metabolism demands energy, so they must eat more often than ectothermic reptiles and amphibians, but the mammals’ adaptability and intelligence easily compensate for their increased energy requirements.

Fittingly Dream now exists as one of the most well-adapted and intelligent mammals of all: a Basilosaurus whale who swims through the warm Tethys Ocean. Someday these waters will separate into the Mediterranean Sea and the Indian Ocean, but in the Eocene Epoch this ancient place is the home of the first cetaceans.

Despite their hairless skin and sleek bodies, whales and dolphins are actually close relatives of the modern-day hippopotamus. Cetaceans and hippos are both artiodactyls - hoofed mammals with an even number of toes - meaning they are members of the same family tree as deer and antelope.

George has also selected an aquatic lifestyle, but he has remained a bird. He is a Presbyornis, a one-meter-tall relative of ducks, geese, and swans. His toes are webbed and his bill is flat, enabling him to filter-feed and wade through marshlands with ease. Presbyornis birds live in colonies, so if one member senses danger nearby, the entire flock will spread their wings and fly away together.

Sapnap can fly too, but like Dream, he is a mammal. The third shapeshifter has adopted the form of a bat: the first mammal to evolve wings for powered flight. He is nocturnal - awake during the nighttime only - but he does not need his eyes to see. A bat’s echolocation allows it to fire bursts of high-pitched clicks that bounce off objects, allowing it to navigate through cramped caves even in absolute darkness. The clicks are too high-pitched for most animals to hear, yet in decibels they are as loud as a jet engine, instantly stunning mosquitoes and moths so the bat can snatch and devour them.

The world has fully recovered from the Cretaceous Extinction. Tentative and hopeful, the shapeshifters each wonder what happened to their companions. The odds are incredibly low that all three of them are alive right now… but if Dream is alive, if George is alive, and if Sapnap is alive, then each shapeshifter assumes it must be possible that their friends survived, too. None of them have knowingly encountered each other in 4.4 billion years, so the search must continue.

Opposite from the artiodactyls, perissodactyls are hoofed mammals with an odd number of toes. Their family tree contains the rhinoceroses, the tapirs, and the equids: horses. These horses are still only sixty centimeters tall, but they are evolving fast. Whereas its ancestor Eohippus browsed leaves in the forest during the Eocene Epoch, the Mesohippus has switched to grazing upon grasslands in the Oligocene. Mesohippus has longer legs and a bigger body, built for sprinting across flat land rather than darting through undergrowth.

George coexists with an entire herd of Mesohippus, blending in with the unsuspecting animals as he has done for billions of years. The early horses migrate through meadows at a casual pace. Most of them chew grass while others in the herd keep watch for predators.

Mammalian carnivores are getting bigger and faster, too. Dream is among them - a Hyaenodon - and he lives alone. The shapeshifter acquired one when he accidentally beached himself upon the shore as a whale, and a prowling Hyaenodon attempted to scavenge from his suffocating body. Nowadays, instead of eating fish and dolphins, Dream hunts prey with legs: camels, pigs, and horses. This afternoon he stalks a herd of Mesohippus, keeping his haunches low to the ground to avoid alerting its lookouts about his presence. Dream’s striped fur blends in with the tall grass. A gentle breeze causes the foliage to sway, concealing the Hyaenodon’s movements as it creeps closer. Patiently Dream assesses each animal for weakness or illness. One Mesohippus is limping, probably due to a thorn in its hoof. The carnivore locks his focus upon it, then -

Abruptly a little horse spooks. It spotted him! Bleating in alarm, the lookout alerts the rest of the herd. They react instantly, leaping away to run.

Unlike herbivorous dinosaurs like Ankylosaurus, who would stand and fight an attacker, mammalian herbivores flee from danger. George startles alongside the others, adrenaline filling his body as a Hyaenodon launches itself toward his herd. The horses dash and split up, sprinting at top speed as the snarling beast chases them.

George stretches his legs forward and back in broad, zigzagging strides. From his peripheral vision he sees the Hyaenodon tackle one of his herdmates: the unfortunate straggler with the thorn in its hoof. Despite his terror, the shapeshifter slows down in relief. He will not become a meal today.

Meanwhile Dream delivers a brutal bite to his prey’s throat. The Hyaenodon’s huge teeth tear the horse’s arteries, swiftly ending its life. As graphic as it is, this is how natural selection has always worked. This Mesohippus was not quick enough, and thus it will not survive long enough to continue its evolutionary lineage.

Crouching beside the corpse, the Hyaenodon begins to eat. In the distance the rest of the Mesohippus have slowed down as well. Alarmed, they watch as Dream rips their herdmate apart, spilling red blood upon the grass. George is among these spectators… but of course, the shapeshifters still have no idea how close they just came to finding each other again. Maybe another opportunity for reunion will come in the future.

Earth’s continents have always been shifting, but at this point in history they would finally be recognizable to humans. The most recent change is the connection of North and South America. For millions of years the continents were separate, so both possessed remarkably different creatures. However, with the formation of what will someday be Panama, both North and South America are now one singular land mass. Without an ocean to prevent them from traveling, terrestrial animals have begun to migrate between the continents in an event called the Great American Interchange.

Dream and Sapnap are both the apex predators of their continents. Dream is a Smilodon: a “saber-toothed cat” from North America. He is a powerfully-built cat with oversized teeth that give him a vicious bite. In contrast, Sapnap is a phorusrhacid: a three-meter-tall “terror bird” from South America. He is a gigantic relative of modern-day secretary birds, reminiscent of the theropod dinosaurs who once dominated the Mesozoic Era.

The Great American Interchange will allow previously unfamiliar creatures to mingle, yet this will inevitably lead to confrontations. Solitary phorusrhacids like Sapnap will be unable to compete with efficient pack-hunters like Smilodon, so the giant predatory birds will become extinct within another million years. Soon the shapeshifter will need to change his form again… but fortunately all three of Theia’s survivors are accustomed to the perpetual need to adapt.

Earth’s climate has cooled. Glaciers creep along the northern and southern hemispheres, covering much of the land with tundra and frost. Biting winds whistle across frozen landscapes, and all of the lifeforms that could not adapt in time have become extinct.

As a wolf, George can easily tolerate bitter weather. Layers of shaggy fur protect him from the harsh cold, and thick paw pads reduce the loss of body heat through his feet. What he does not want to tolerate is starvation.

In the icy spruce forest where the shapeshifter lives, all birds and rabbits are either hibernating or hiding in tunnels underground. Hoofed mammals like deer and buffalo gather in herds, so they will definitely notice the predator’s approach before he can move close enough to strike.

Survival as a lone wolf would be difficult in the ice age… if George had not found a different type of ally to accompany him. Instead of traveling alone, the shapeshifter has joined a community of humans.

Whereas most wolves are hostile toward the Earth’s newest apex predator, the more docile wolves were curious: eager to exploit an opportunity for guaranteed food, shelter, and safety. These particular wolves became the wild ancestors of domestic dogs.

Sometimes the humans are nomads, migrating from place to place just like other animals. Sometimes they construct shelters with wood and pelts. Regardless, George lives alongside them; he assists human hunters, and in return they give him a portion of the resulting carcass. The wolf does not understand most of the human’s mouth sounds, but he has learned that certain noises and hand gestures mean important things. George recognizes commands which mean “come here”, “stay there”, and “track this scent”.

Sapnap also lives among a community of humans, but not as a wolf. Instead he exists as one of them. When he was a snowy owl a few years ago, he encountered a lone human who was lost and injured. Sapnap swooped onto the ground beside it and acquired the human before it died, then he navigated by memory to the closest human settlement only a few kilometers away. Cold and shivering without clothes, the shapeshifter was already regretting his decision before the other humans noticed his arrival. Although Sapnap could not decipher their language yet, they greeted him and coaxed him into their community. He received leather boots, a coat made of pelts, a sharpened piece of flint, and a woven basket full of dried berries to eat. Sapnap was unfamiliar with the concept of charity, but he welcomed it, and immediately he gained a sense of loyalty to the other humans that he had never felt toward any other Earth creature.

Sapnap stays with this community for years. Of course, this quantity of time feels like nothing to him, but the other humans seem to develop a sense of awe toward the former stranger. The shapeshifters never age, yet until now, no other creature noticed. Eventually the young humans become older, the old humans become elderly, and the elderly humans become corpses… but Sapnap remains strong and keen. Therefore the community elects the former stranger to become their leader.

Together the humans survive snowstorms, they defend themselves from cave bears, and they gather resources to feed their offspring. Sapnap is responsible for conducting hunts, so today he guides the community’s able-bodied adults beyond their camp in search of food. Young parents stay behind, wrapping their babies in pelts to keep them warm while older parents supervise the children. Disabled individuals remain behind as well, tending to the fire and repairing the camp. Unlike most animals, who would not attempt to aid an injured rival, humans have evolved extraordinary social bonds to support every member of the community.

This particular group of humans also had wolf allies like George to assist with tracking prey, but a fatal encounter with a local pride of American lions resulted in the wolves’ untimely demise. In the end, however, the wolf population as a whole will prevail; in another 2,000 years, American lions will be completely extinct.

Furry pelts cover most of Sapnap’s body, shielding his skin from the brutal cold while he walks. Leather boots plunge into snow and crunch upon the gravel beneath it. Dry knuckles grip the wooden handle of a spear. At the weapon’s tip is a sharpened piece of flint, tied to the handle with knotted twine. Sapnap leads a single-file line of humans, hiking through the dormant forest. Soft dawn light glistens on icicles which hang from branches. Ragged breaths billow from human lips, alerting all nearby animals about the humans’ presence, but this fact is irrelevant. Solitary predators might depend on stealth to guarantee a successful hunt, but humans rely on the opposite strategy: endurance.

Muscles loaded with fast-twitch fibers make cheetahs and gazelles some of the swiftest animals on the planet. Fast-twitch fibers also burn energy quickly, so neither cheetahs nor gazelle can maintain their top speed for longer than a minute or two.

Humans have muscles loaded with slow-twitch fibers instead. Therefore they cannot accelerate as rapidly as other mammalian predators, but they can maintain their top speed for much longer. Additionally humans possess the ability to sweat, sacrificing a little extra water so the evaporation can cool their skin and prevent overheating.

Humans are also uniquely bipedal. Longer legs and thinner arms mean that walking on four limbs is now awkward and cumbersome, but dexterous hands and a curved spine make carrying things incredibly convenient. Whereas their primate ancestors had shoulder blades on the sides of their ribcages for quadrupedal movement, human shoulder blades have moved behind their ribcage. This unusual bone structure enables humans to throw objects farther and aim more accurately than any other mammal. All of these adaptations are necessary for Earth’s newest apex predator to succeed at difficult hunts like this one.

Sapnap’s group reaches the edge of the forest. Spruce and pine trees become sparse. No more spindly branches block the morning daylight. From here the humans can see the horizon, where icy meadows stretch until they crawl up the base of a mountain range. A distant herd of elk rummage through snow with their snouts, grazing upon the frozen grass and lichens below it, but the large deer will not be the humans’ target today. Sapnap wants to pursue something more substantial… like a mammoth.

Ahead a lone mammoth migrates through the meadow, absently flapping its tiny ears. Asymmetrical curving tusks protrude from its face. White powder collects along its sloping spine. Shaggy brown fur hangs from its enormous body, and there is enough meat beneath it to feed the humans’ community for months.

Sapnap makes a hand gesture, and the single-file line behind him splits up. Not trying to be subtle, the humans spread out in a semicircle formation. Each member of the group grabs their knife or spear, but no one runs. They do not need to chase the mammoth; all they must do is corner it. Sapnap gives another hand gesture, and they all pursue the mammoth together, maintaining their semicircle formation so the huge creature cannot flee sideways.

The mammoth spots them within seconds. It stops walking, and it turns its head to assess the approaching creatures. Sensing the potential danger, the mammoth trumpets in warning.

Still the humans do not attack it directly. Instead they simply march forward, using their extraordinary intelligence to plan ahead. The mammoth’s size protects it from most threats, but that same size also prevents it from climbing steep slopes. Therefore the humans will drive it toward the mountains, where the mammoth will inevitably become trapped and forced to fight for its life. By then it will already be exhausted from stress, and the humans will strike with a much better chance of success.

However, after ten minutes of careful corralling toward the mountains, the mammoth becomes wary. Sooner than expected, it turns to confront the humans. Usually the mammoths do not realize their doomed situation this early.

Caught off-guard, Sapnap gives another signal. The humans stop walking, ready to flee in case the mammoth charges. The group leader is perplexed and suspicious as the creature gazes at him, apparently aware that this particular human is the one giving orders.

Sapnap circles around the mammoth, tightening his grip on the spear. Can he impale its throat from here? He wants to wait for a clear shot.

As the human moves, the mammoth does another unexpected thing. Tentatively it turns to face him, and it reaches toward him with its trunk. Delicate like a pair of tweezers, the trunk plucks Sapnap’s spear from his grip. Instinctively the human releases it; if he clung to the handle, the mammoth could pull him off-balance and crush him.

Flinging the spear, the gigantic herbivore tosses the weapon aside. It sticks into the snow several meters away, far beyond Sapnap’s reach. Spooked, the human starts backing up.

Too late. The mammoth reaches toward him again, but this time its trunk wraps around his wrist. As gently as if another human were gripping it, the trunk curls inward. Hairy skin glides against Sapnap’s bare forearm. The human stiffens, preparing for the mammoth to throw him too, but instead the mammoth simply waits.

Suddenly a strange tingling sensation occurs in Sapnap’s wrist where the mammoth’s skin is touching his own. The shapeshifter is not trying to acquire the mammoth, though. It is almost like the mammoth is trying to acquire him.

Stunned, Sapnap jerks his head up. He stares into the creature’s eyes, connecting pieces of a puzzle together. This mammoth’s situational awareness, its curiosity despite its fear, and the radioactive energy that seems to accompany its touch? Perhaps it is not really a mammoth at all. What if it’s -?

Experimentally Sapnap tries to acquire the mammoth, and within an instant the trunk detaches. As if he had electrocuted it, the mammoth withdraws with a snort of surprise. It felt the sensation, too!

After 4.5 billion years, two imposters recognize each other. Despite their different bodies, they know exactly what a shapeshifter’s touch feels like.

Who are you? Sapnap yearns to ask. How did you survive for so long?

Internally Dream is wondering the same thing. Is this human really his long-lost friend? Although the shapeshifters wonder how both of them managed to evade multiple extinction events, the answer is actually obvious. Dream and Sapnap survived because they promised to find each other… but they cannot fulfill their promise yet.

Abruptly aware that the other humans are waiting for his command to kill the mighty beast, Sapnap gives the order for his group to retreat. Keeping a hand close to his chest so his body will conceal it, Sapnap catches the mammoth’s gaze. Secretly he points toward the distant herd of elk as if to imply, “Choose one of those.”

Flapping his ears in understanding, Dream replies with a deep rumble of gratitude, then he turns away from Sapnap. Lumbering around the semicircle of humans, he approaches the herd of elk to change his form.

When Sapnap returns his attention to the group, they stare at him in confusion and wonder why he cancelled the hunt, but of course he cannot share the truth. Instead the leader simply explains, “It spoke to me.” This is not a complete lie, and the rest of the group accepts the answer. Sapnap is their leader and he is very wise, so they shall trust him.

Instead of pursuing another mammoth, the group continues their search for a smaller creature to hunt. Sapnap instructs a different human to lead their single-file line through the forest while he chooses a spot in the back. Stuck in a haze, he follows the other humans, struggling to focus after the unexpected encounter.

His friend from Theia is still alive. Sapnap looked directly at him. He cannot believe it, and even though they could not reunite, at least Dream and Sapnap know they were not the only survivors of the apocalypse. Both shapeshifters still travel through the world, adapting to the environments around them… and if two shapeshifters managed to make it this far, then where is the third?

Gradually the globe is warming, and the ice age has ended. Glaciers receded and the snows melted, so all lifeforms accustomed to perpetually cool weather had to migrate, adapt, or die.

Along with the environmental shift, another change spread across the world, too. With their combination of unbreakable social bonds, bipedal body structures, and enough intelligence to create and use tools, humans have become the Earth’s dominant terrestrial species.

Sapnap has remained in a human form since the Pleistocene, but his most recent acquisition was a young male from Greece during the Roman Empire. Since the shapeshifter’s body never ages, he must move from place to place every decade and adjust his appearance so no one else will notice his eternal youth.

One of the humans’ greatest strengths is knowing how to compensate for their weaknesses. Civilizations around the world domesticated cows, llamas, camels, sheep, silkworms, pigs, horses, and goats into crucial allies for their global expansion.

Like millions of other humans around him, Sapnap lives with a dog: a distant descendant of the Pleistocene wolves. Every day he walks through the neighborhood with the dog by his side, but he never needs a leash. Strangers compliment him frequently, commenting that his dog is “so well-behaved” and “very well-trained”. Sapnap always thanks them politely, but of course, he never actually trained his dog to do anything. It is not even a real dog at all.

Dream and Sapnap found each other again several centuries ago, while one shapeshifter was a sailor fleeing the bubonic plague in Europe during the 1300s and his counterpart was a rat on the ship. Once reconnected, the long-lost friends have been inseparable ever since.

This afternoon Sapnap is cleaning the back porch of his house. He propped open the door with a chair, allowing Dream to watch from where he relaxes on the couch. Despite his dog form, the other shapeshifter behaves remarkably like a human. He never bites, he rarely barks, and Sapnap knows that if any trouble finds him, Dream will not hesitate to protect his friend. Therefore, when the dog suddenly lifts his head off the couch’s armrest, Sapnap raises his attention, too. “Dream?”

The dog’s black nose twitches. His eyes focus on something behind his friend. Alert, Sapnap stands straight up and turns his head to follow Dream’s gaze.

Across his backyard, a small shape slinks out of the bushes. A cat appears, cautious yet curious, keeping its body close to the tall wooden fence.

Nothing dangerous. Sapnap relaxes with relief, then he kneels. Softly he greets, “Hi, kitty. Do you have a home?”

The cat curls its tail. It meows.

“You seem friendly.” Sapnap clicks his tongue to beckon it. “I keep an extra can of cat food inside for strays. Are you hungry?”

Finally the cat gains the courage to approach. Meowing again, it trots across the grassy backyard toward the porch, where Sapnap extends a hand in offering. The cat slows down when it reaches him, stretching its neck to sniff his hand… then it reacts.

Suddenly the cat scrambles back a few steps. Its eyes open wide, its pupils dilate, and its fur fluffs up.

“Woah, kitty. It’s okay.” Lowering his voice, Sapnap reassures, “Do you smell the dog? Don’t worry, he’s friendly.”

The startled cat stares at his face, then it releases its loudest meow yet. Launching itself forward, it surprises Sapnap by weaving around his ankles and calves. Thick purrs emanate from its throat, so the human pets it… then he reacts, too.

A tingling sensation: radioactive energy. No Earth creature feels like this.

“Wait. Are you -?” Sapnap’s jaw drops with astonishment. “George?”

Meowing and purring, the excited cat rubs its face against his knee.

“Oh my god, it’s you!” Overjoyed, Sapnap yells, “Dream, come here!”

Equally thrilled, Dream is already rushing out the door. The dog dashes toward the cat, sniffing its fur and whining with delight. After what felt like an eternity of searching, George has found his friends again.

“How did you find us? Did you know it was us?” Overwhelmed, Sapnap cannot believe the odds… yet at the same time he can. The shapeshifters have traveled across the world again and again, existing in millions of forms and bodies, experiencing billions of years and lifetimes. Ultimately their separate, parallel journeys led to the same place: this moment right here, right now.

“Well, I guess we have plenty of time to catch up on everything.” Sapnap scoops George into his arms and carries him inside. Dream barks once in jubilation, then the human closes the back door behind them. “It’s good to see you again, buddy. Now let’s finally get you some good fucking food.”

Eager to show George their neighborhood and its sights, Sapnap brings his dog and cat to the local natural history museum. Dream wears an “emotional support animal” harness while George pokes his head out from the main compartment of Sapnap’s backpack. Technically non-human lifeforms are prohibited in the museum, but clearly the museum staff are not paid enough to care because no one protests when they buy a ticket and step inside.

Sapnap and Dream have visited this museum before, so they rely on George to decide their pace. Whenever the third shapeshifter wants to pause, he presses a paw against the side of the backpack which touches Sapnap’s spine. Then when George is done looking or reading, he removes his paw, and the friends continue their exploration.

The natural history museum is arranged in chronological order, so the first exhibit is about the formation of the Earth. Sapnap, Dream, and George gaze upon diagrams and video recreations of Theia, the moon, and the solar system. They witness exhibits about the Hadean Eon, the Archean Eon, “Snowball Earth”, and the Ediacaran Period. They examine murals about the evolution of life on Earth, from single-celled organisms to cyanobacteria to plankton to multicellular organisms. Reliving those first few billion years in their minds, the shapeshifters simply nod in appreciation and move along.

Next are the rooms dedicated to fossils from the Paleozoic and Mesozoic Eras. A glass display contains skull fragments from Smilesaurus and Gorgonops: synapsids of the Permian Period. Both George and Dream pause to gaze upon them.

Sapnap’s favorite exhibit artifact is the Tyrannosaurus skeleton. That was one of his favorite forms, yet it was among the last dinosaurs to exist. As the shapeshifters remember their desperate scramble to survive the Cretaceous Extinction, Sapnap mutters, “Yeah, that was a shitshow.”

Despite those terrible memories, nostalgia rises within the three friends regardless. Now that they know they were apart but alive, recalling their helplessness ignites a complex mix of emotions. They saw lifeforms evolve and go extinct. They saw everything live and die around them. Throughout their lonely lifetimes, all three friends frantically hoped they would eventually find each other again… and then they did. The shapeshifters have reunited and fulfilled their promise, so now everything will be okay.

Before the shapeshifters gained the ability to change their forms, they were merely three souls in a cavern below Theia’s surface. Uncertain and petrified, the microscopic organisms overlapped, clinging to each other as they prepared for the apocalypse.

4.5 billion years later, the former planet’s three survivors curl up together once again, but this time the atmosphere is far different. Instead Dream, George, and Sapnap are comfortable and happy, delighted to simply enjoy their existence together.

Tranquil and safe, all three mammals lay on Sapnap’s couch in his house. Splayed on his back, the human is on the bottom. A snoring dog drapes over his waist while a purring cat snuggles against his arm.

The shapeshifters have fought to survive, they have fought to escape, and they have fought to find each other… but they do not need to fight anything at all anymore. Now Dream, George, and Sapnap can just cuddle and fall asleep together while life on Earth continues around them.