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Schrödinger’s Todoroki

Summary:

At a young age, Shouto Todoroki finds out that his supposedly dead older brother became a villain. In high school, he investigates the League of Villains. His keen conspiracy theorist skills realize that Touya Todoroki must be the white-haired villain related to a hero…Tomura Shigaraki!

Dabi spontaneously combusts from sheer rage.

Notes:

This title was submitted to me in an ask game by BlueRose0justBlueRose / blue-roz-blog, then somehow became a full fic. Thank you to my sister for brainstorming ideas with me.

Work Text:

The Todoroki mansion had cameras everywhere. Of course the residence of the number two hero had security. But ever since his oldest son’s death, Enji Todoroki had thrown himself into work, training Shouto, and heavy drinking. He hadn’t bothered to watch the camera footage in years.

In most universes, Enji never noticed a teenage Touya sneaking into the mansion to pray before his own altar. In one, Enji checked his cameras, then nearly had a heart attack.


Shouto Todoroki crept down the hallway. His father hadn’t come to his room to force him into training today. Little Shouto longed for a break for one single day. He was quite happy to be forgotten. But his stomach had started rumbling, until he’d given into his hunger and headed downstairs to the kitchen for a snack. He tip-toed past his father’s office so as not to draw the attention of the beast.

Enji’s loud, angry voice drifted from inside: “Yes, I’m certain it was Touya! Even with the scars, even years later, even in a blurry camera image, I know my own son.”

Shouto froze, one foot in the air. This was interesting.

Enji continued, “I’ve searched every hospital for burn victim patients without luck. Touya must have been picked up by a villainous organization. I’m worried—what if he came back to the mansion for Shouto?”

Shouto’s big brother was alive! And a villain! And he’d returned home for Shouto’s sake? Shouto’s heart hammered. He wasn’t happy. He’d be willing to leave this place with anyone, even a villain. If only Touya had succeeded in taking him away.

“The mansion needs much heavier security to protect Shouto. Let me find our blueprints. I’ll send you a copy.” A rustling came from inside as Enji’s chair pushed back and he stood up.

Shouto leapt away, fleeing down the hallway to avoid detection. Shouto never heard the part of the conversation where Enji admitted to the HPSC president that Touya had tried to kill Shouto as a baby. When Enji added cameras to Shouto’s window and spent more time at home, it only made Shouto angry that his last bit of privacy had been stripped away.


Shouto was on a mission: to find out information about his oldest brother, Touya Todoroki. But Touya was a taboo subject in the Todoroki household. Shouto nagged Natsuo relentlessly without getting anything except anger in return. Fuyumi said that Touya had inherited a body like their mother’s that was weak to fire, that he’d felt rejected by their father for having the wrong quirk, and that he’d burned to death. She’d looked so sad that Shouto didn’t press her any further.

From these scant three facts, Shouto concluded that Touya must not have had a fire quirk. Otherwise he should have been less flammable. Perhaps Touya had a rare mutation that caused him to develop a different quirk from either of their parents. No wonder their quirk-obsessed father had rejected his oldest son. If Touya could have any quirk, that would make it much more difficult to find him. But at least Shouto could eliminate all villains with fire quirks.

For years, Shouto kept a corkboard in his room with a list of every single known villain in Musutafu close in age to Touya. He listed the evidence for and against each suspect and removed them from the board as he eliminated them. In the beginning, Shouto had searched for his big brother so that Touya would protect him and take him away from their abusive father. Later, Shouto realized the impracticalities of living with a villain if he wanted to become a hero. But he never gave up on his search. It was partly curiosity, partly stubbornness, and partly a longing for family.

Shouto’s search had faded from an obsession to a hobby over the years. Then in high school, he overheard a whispered conversation between his father and the HPSC President about Touya resurfacing as a member of the League of Villains, and Shouto was back on the trail.


Kurogiri was standing behind his bar polishing a glass when a red-and-white head poked up over the counter. “How old are you?” the strange boy asked. “You look a little old to be Touya.”

Nearly dropping his glass, Kurogiri demanded, “How did you find this place? Aren’t you a hero student?”

“Shhhh.” The boy placed a finger to his lips. “I’m incognito.” He wore a black hoodie and sweatpants. “I taught myself hacking skills and developed a network of informants so that I could track down my missing older brother. Nice hideout you have here. Do you have shadows around your face because you’re hiding your true identity as Touya Todoroki, son of the number two hero?”

Kurogiri stared. “No.”

The boy tapped his nose. “That’s exactly what Touya Todoroki would say.”

Kurogiri asked, “If I answer your questions, then will you promise not to tell the police where to find my bar?”

“Deal,” the boy said.

“I’m fifteen years old.” That was the number of years since Kurogiri had woken up in Dr. Garaki’s laboratory. “Also, I don’t have a father.”

“Huh, you’re too young, not too old. I didn’t see that coming.” The boy scratched off a name on his notebook. “Next!” He shot off in a blur.

Kurogiri considered chasing after the kid, then remembered that he wasn’t paid enough. In fact, Kurogiri wasn’t paid at all.


Spinner and Magne sat on the couch playing video games. A teenager with a scar and half-red, half-white hair burst into the room, the door bouncing off the wall. “You’re about the right age!” he cried, pointing at Spinner. “Could it be that our dad rejected you because he believed you weren’t his real son, because of your mutation?”

Glancing up, Spinner said, “My father has the same gecko quirk as me.” Then an explosion drew his attention back to the TV screen.

“Oh, well.” The teenager turned to Magne. “Big sister! Even if Mom and Dad’s overly traditional families refused to accept you, I’ll still—”

Magne said, “I’m an only child.” She stuck out a hand to stop the boy from hugging her.

“Never mind.” The boy shot out of the room in a blur.

Spinner asked, “Did a stranger invade our secret base? Should we do something about that?” Then Magne delivered a punch to his character, and he focused his attention back on the game before he died.


Mr. Compress stepped into his bedroom. After locking the door, he took off his heavy mask and ran a hand through his sweaty hair.

From the ceiling, someone said, “What a shame. I had high hopes for you because you wear a mask, but you don’t look anything like Touya.”

Mr. Compress looked up. A scarred boy clung to the ceiling light. “How did you get in here? No one sneaks past me! I’m an expert at concealing my presence!”

“One more name down.” Smoke billowed off the boy, then he vanished. A smoke bomb clattered on the floor.

Mr. Compress shot out a marble, but too late. He shouted, “Come back! You have a natural talent for magic! Please become my apprentice!”


Twice reclined in an armchair while Toga painted his nails pink. They both looked up as the living room door flung open. The scent of smoke clung to a red-and-white haired boy. Pointing at Twice, he demanded, “Do you suffer from identity issues because our father rejected you?”

“I never knew my father,” Twice said, followed by, “For once, I agree with myself. The deadbeat wouldn’t have wanted to show up for my conception.”

“Aw. Another perfectly good conspiracy theory, gone.” The boy’s shoulders sagged. Without much hope, he asked Toga, “I don’t suppose you’re secretly an adult man shapeshifting into a high school girl?”

She laughed as she capped the nail polish bottle. “No way! That would be creepy even for me!” Her twisted grin widened.

“I didn’t think so.” The boy crossed off two more names in his notebook. “My older brother is a member of the League of Villains. All I know about him is that he doesn’t have a fire quirk, so he can’t be Dabi.”

“Aren’t you Izuku’s friend?” Toga’s eyes widened. “Todoroki, right? If you tell Izuku that I love him, then I’ll help you figure out who’s your long-lost brother.”

“Deal.” Shouto sat down in the chair across from Toga.

As they chatted, Twice mumbled, “Is it okay for a hero student to be here?” followed by, “Who cares? I can’t fight with him, I might smudge my nail polish.”

“I think I’ve figured it out,” Toga said. “Shigaraki told me that he took on his teacher’s last name, and that he changed his first name. He also got a little drunk once and said that he was related to a hero and that has something to do with why he wants to destroy society.”

“It all fits!” Shouto clapped his hands. “Tomura Shigaraki has white hair! He has a destructive quirk likely to be stereotyped as villainous and unsuited for heroics! He clearly got the family theater kid genes!”

As Shouto ran out of the room, Toga called, “Please stab Izuku a few times when you send him my love!” Turning back to Twice, she said, “He seems nice.”

Twice agreed, “Yeah, we probably shouldn’t hurt him if he’s the boss’ little brother.” Twisting, he growled, “I’d kill him with my own two hands except my nails are still wet.”


Rummaging through the kitchen cabinets, Tomura demanded, “Who took my last bag of wasabi potato chips?” At the moment he was handless, since Kurogiri had forbidden severed dead body parts in the kitchen. He wore jeans and an Eraserhead shirt.

A suspicious crunching sound came from the hallway. Tomura yanked open the door to find Dabi just as he tossed the last potato chip into his mouth. Licking his fingers, Dabi said, “I didn’t see your name on them.”

“Everyone knows that’s my snack drawer,” Tomura growled. “Those were limited edition! I’ve been saving them and carefully eating only one bag a month for years! That was my last bag!”

“They weren’t even that good.” Dabi carelessly tossed the empty bag to the floor.

“Oh, it’s on now.” Tomura started to yank off his glove.

A red-and-white blur shot into the room. Shouto flung his arms around Tomura and cried, “Big brother! I finally found you!”

Sheer surprise froze Tomura in place. No one had hugged him since All for One had ordered Kurogiri not to do that. It felt warm and suffocating and gave him strange feelings.

Leaning into Tomura’s chest, Shouto sobbed, “I just want you to know that I’ll always love you even if you’re a villain. Please, come home with me.”

“What the—” Tomura mumbled, his brain starting to reboot.

The air sizzled as smoke rose off Dabi’s hair. Dabi growled, “Excuse me? That hollow cosplayer could never be the magnificent Touya Todoroki!”

“Of course this is my big brother.” Shouto stepped back and gestured at Tomura. “Just look his white hair and natural good looks. That’s the Todoroki family charm.”

“I’m way better looking than the Hand Freak! I’m Touya Todoroki!” Dabi cried. “Ugh, now you’ve ruined my big reveal. I had a dance routine planned and everything.”

Shouto crossed his arms. “I don’t believe you.”

Dabi screamed, “I HAVE A FIRE QUIRK!”

Shouto shook his head sadly. “If only Touya had a fire quirk, then he probably would have been Dad’s favorite and adored son instead of being thrown away as a failure.”

An unearthly howl rose from Dabi’s throat. Flames covered his body, burning away the skin to show the bone underneath. Flames wreathed his mouth like a horrid smile, melting his gums to reveal his teeth.

“Oh my god, we have to help him.” Ice formed on Shouto’s palm.

“Nah, don’t bother,” Tomura said. “Dabi spontaneously combusts whenever he gets angry. Last time, it was because I beat him at a video game. He always pulls his ashes back together in a few minutes to an hour. It actually hurts his body if you interrupt the process—you have to let him complete burn out before he’ll reform. Kurogiri thinks that he has a phoenix quirk.”

“How fascinating,” Shouto said. “It’s a shame you don’t have a phoenix quirk, big brother. Then you never would have burned up at Sekoto Peak.”

Dabi, who’d been starting to reform, spontaneously combusted from sheer rage again.

A tiny, mean smile formed on Tomura’s lips as he contemplated revenge for his stolen potato chips. Speaking at Dabi’s ashes, he said, “I’d like to get to know you better, little brother. Why don’t we head to a café and have a chat?”

“Whoa, I’d love that!” Shouto said, starry-eyed. Dabi’s strangled howls followed them as they left.


In the café, Tomura leaned back and put his feet up on the air conditioner. He sneered at the boy across the table from him. He’d only done this to annoy Dabi, and now he had no idea what to say to the hero brat across the table from him. Tomura hated wannabe heroes, but he couldn’t just decay Dabi’s little brother, no matter how pissed off he might be with his comrade. Not when Tomura knew what it felt like to lose a sibling. He cleared his throat. “So, uh…what happened with, uh, our family, after I, uh, left?”

Shouto immediately poured out a truly horrible and depressing tale of child abuse and how he’d gotten the scar on his face. With each word, Tomura straightened up. His stomach rolled. He knew exactly what it felt like to live under the rule of a tyrannical father. This wasn’t something he could sneer at.

Scratching at his neck, Tomura said, “Uh, that sucks.” For the first time in his life, he wished he’d learned better people skills. That had been lame.

Shouto looked down at his hands, trembling on the table. “After Dad said that you’d returned to the mansion, I used to dream for years that you’d come back and take me away from that house. Big brothers are supposed to protect the younger ones, right? I thought maybe you could save me from Dad.”

Those words hit Tomura like a gut punch. He flashed back to his time as a child wandering the streets and waiting for someone to help to him. What should he say to answer the question in this boy’s eyes? Tomura had no idea why Dabi had never returned to his family. Suddenly he regretted his stupid prank. “I…”

“It’s okay.” Shouto tried to smile, even though tears were glistening in the corners of his eyes. “I know that you must have had it rough living on your own. You probably could barely protect yourself, much less me. But maybe from now on we can look out for each other? Would it be okay if I came back to visit you again?”

Tomura simply didn’t have it in him to say no to those tear-filled eyes. He ought to admit the truth, but the words refused to come out. Slouching down, he whispered, “Okay.”

“Big brother!” Shouto flung his arms around Tomura. Slowly, Tomura’s gloved hand went up to pat his back. This felt…kind of nice.


When Tomura returned, Dabi greeted him at the front door, reformed but still sizzling. “You’d better not have killed him!”

“I didn’t hurt your little brother,” Tomura said. “I shouldn’t have meddled in your family affairs. I’m sorry.”

“Sorry?” Dabi’s flames extinguished from shock.

Hanging his head, Tomura walked past him. “I’ll tell the kid the truth. He gave me his cell phone number, so we can call him together. Then you two can become brothers again.”

“Who the hell wants to play family with Daddy’s precious masterpiece?” Dabi laughed cruelly. “I didn’t want you to kill Shouto because I plan to do it with my own two hands.”

Tomura whirled around. His face turned pale as his hair. “What?”

Dabi sneered. “I’m going to break Endeavor’s spirit by showing him his son’s corpse.”

“But that’s your little brother!” Tomura cried. “He was a victim of your father, too.”

“Who cares?” Dabi shrugged. “He’s nothing to me. Killing him will be nothing but a means to revenge.”

Tomura slammed his fist into the wall so hard the paint cracked. His hair fell over his face. He growled, “You have no idea what it means to kill a sibling! You don’t know what it’s like to watch her decay away. To hear her last cry before she vanishes into thin air. To wear her hand on your body every single day. To lie in bed on her birthday every year, unable to get up, thinking ‘If only, if only.’ To want to burn down the world because she’s no longer in it. I would do anything to take it back, and you’d just throw your little brother away!”

“…Are we still talking about Shouto?” Dabi asked.

Tomura’s face contorted into a snarl. “You’re a deadbeat brother! Shouto is my little brother from now on!”

“You can’t do that!”

“You stole my potato chips, so I’m stealing your brother.”

Dabi moaned. “Just how much of a petty grudge are you holding over your stupid wasabi-flavored chips? They didn’t even taste good! My taste buds are mostly dead yet they’re still aching.”

“Apparently Shouto is worth less than a potato chip to you, deadbeat, so we’ll call the trade fair. Go ahead, try and tell him the truth. Who do you think he’s going to believe?” Tomura strode down the hallway, shouting, “From now on, Shouto Todoroki is off-limits! Did everyone hear that?” As Dabi spontaneously combusted again, Tomura added, “Kurogiri, get the dustbin and the mop again.”


Shouto stood outside the front gate of the amusement park, looking at his watch.

Tomura jogged over. “Did you wait long?”

Shouto’s head shot up. “No! I’m happy to see you, big brother.”

“Aw, you’re such a cute kid.” Tomura patted Shouto’s hair, his face gentle. “Come on, the tickets are on me. It’s a big brother’s responsibility.”

Crouched down behind a bush and watching, Dabi muttered, “What an idiot! He has no idea how to be a proper older brother. You can’t just give the little brats whatever they want, you have to uphold your authority. Also, amusement parks are lame. I bet Shouto doesn’t even like amusement parks.”

Shouto said, “I love amusement parks! Thank you.”

Dabi burst into flames. Tomura put an arm around Shouto and turned him away before he could notice the combusting villain.


By the time Dabi pulled himself back together, he realized that he’d burned up all his money. He couldn’t get into the amusement park. Instead, he sulked behind the bush and glared at the park gate. People pointed and whispered. Dabi smoldered. It wasn’t fair! Just because Dabi didn’t want Shouto as a little brother didn’t mean anyone else could have him either.

Toga tapped Dabi on the shoulder.

He whirled around. “How the hell did you find me, whacko?”

She grinned, flashing fangs. “I’m a professional stalker. Aren’t we supposed to be holding a meeting about attacking U.A. right now? Our boss wandered off and you followed him.”

“I have bigger priorities.” Dabi leapt up as Tomura and Shouto walked out of the amusement park.

Shouto’s arms were full of toys and stuffed animals. “You’re great at games, big brother. But I feel a little bad for the man running the shooting game. He started crying after you won all the big prizes.”

“When I have such a cute little brother watching, of course I have to show off my skills.” Tomura chuckled. “Don’t feel sorry, all those games are rigged.”

Shouto gazed up worshipfully. “You’re so cool, big brother.”

Angry hisses emerged from Dabi’s mouth. He muttered, “He’s spoiling Shouto! Now the stupid brat will expect presents all the time.”

Crouched down, Toga said, “Yeah, and it’s not like you could win those rigged games.”

“I could if I wanted to!” Dabi insisted. “I just don’t want to because I hate Shouto. I’m not like some people who fawn over their little brothers who aren’t even their little brothers.”

“You can’t lose if you’re not trying?” Toga giggled mockingly.

“That does it!” Dabi marched over to Tomura and Shouto. “This has gone on long enough. I’m the real Touya Todoroki! I’m your long lost brother and the man who will destroy Endeavor!”

Shouto snorted. “My brother Touya has white hair.”

“That’s right.” Tomura put his arm around Shouto’s shoulder and smirked. “Ignore this complete stranger who is no one to us. I’ll protect you from Endeavor.”

“Why you dried-up handjob! Watch this!” Dabi pulled out a bottle and tried to pour it over his head, except he was so angry that flames rose off his body and the liquid evaporated. Screaming in frustration, he spontaneously combusted into a pile of ashes.

As horrified gasps and cries came from the bystanders, Tomura pulled Shouto away. “Sorry about him. The League of Villains only keeps him around as a pity case. Would you like to go out for soba?”

Shouto gasped. “I’d love to, big brother.”

Moans came from Dabi as his ashes kept trying to pull themselves together only to burst into flames again with each word.

Filming on her phone, Toga said, “This is way more entertaining than attacking heroes!”


Dabi did not like going to Dr. Garaki for checkups, but after so many times burning up in a row, he swallowed his pride and let the doctor examine him.

While Dr. Garaki’s back was turned, Dabi snuck over to his computer and searched for files with Tomura’s name. Ah-ha! He found a family tree. Apparently Tomura Shigaraki was cousins with someone named Izuku Midoriya. They shared a common grandparent, Nana Shimura. Dabi’s eyes widened as he read about All for One’s child support payments. Izuku Midoriya was a double little brother to Tomura Shigaraki! Even more worth stealing!

With a huge smirk on his face, Dabi formed his revenge plan. He wouldn’t let Tomura find out about his relation to Izuku until it was too late. Then they’d see who was the ultimate big brother!


As Izuku walked down the sidewalk, he heard a rustling from the bushes. “Psst! Kid!”

Looking down, Izuku saw Dabi crouched behind a rhododendron. The villain grinned, stretching the staples on his face. “Want to be my new little brother? I’ll buy you gifts!”

Izuku pulled out his phone and dialed. “Hello? Mr. Aizawa? I’m being attacked by a villain. What, no, I’m not a fake! What do you mean, ‘The real Izuku Midoriya would never ask for help, he’d just fight the villain on his own’? Don’t hang up on me! This is literally why I have trouble trusting adults.” Sighing, Izuku lowered his phone. “Fine, it looks like I’m fighting you after all.” He raised his fists.

“Whoa, I’m not here to fight.” Dabi held out two tickets. “I did my research on you. These are exclusive tickets to the advance screening of the new All Might documentary. Say that you’re my little brother, and you can come with me.” Under his breath, he whispered, “Ha, Tomura would never be able to sit through an All Might documentary! Who’s the best brother now?”

Izuku’s jaw dropped. He drooled with desire. Wiping away the saliva, he smiled brightly. “Why didn’t you say so sooner, new big brother?”


OMAKE TIME!

Omake: All for One’s A+ Parenting

Tomura: Sensei, I keep having nightmares about my sister’s face. I just want the pain to stop.

All for One: Guilt, huh? I quit that cold turkey a century ago.

Tomura: I miss Hana.

All for One: Have you considered replacing her? I knocked up my archnemesis’ daughter to get myself a replacement brother.

Tomura: Sensei, I’m eight years old.

All for One: I’ll buy you a goldfish.

Tomura: I want a corgi.

All for One: You can’t have any pets that might chew on my nice shoes or teach you empathy. Take your goldfish and flush it down the toilet if you don’t like it.

#

Omake: Meet the League of Villains

Tomura: Everyone, this is my new little brother. I mean the little brother I’ve always had but never mentioned before.

Mr. Compress: He can be my little brother too if he agrees to become my apprentice.

Toga: I’ll be your big sister!

Magne: I’m jumping on this bandwagon too, because hey, why not?

Dabi: Hey! Just because I don’t want my little brother doesn’t mean I’ll share him with all of you!

#

Omake: The True Winner

Dabi: It looks like I win the title of best brother.

Tomura: You tried to kill your brother! You can’t make up for that with a few movie tickets.

Dabi: Yet only one of us here has actually murdered a sibling.

Tomura: Let me at him! I’ll kill him!

All for One: If we’re competing for best big brother, then I—

Yoichi: Nope.

All For One: I’m clearly—

Yoichi: Shush.

Tensei: (Wheeling in like a king on his throne and wearing a crown) Did someone call for the best brother in My Hero Academia?