Work Text:
Kai stares unimpressed at the squirming form on the bed, the fool should know it’s futile to struggle, only serving to chafe his own skin. “Stop struggling, you’ll only hurt yourself”, watching impassively as the man squirms even more. “Fuck you! You lied to me!”, Shigaraki snarls from the bed, tied onto his back, for a prime the man is not particularly well built. All skinny and lean muscles, although still bigger than the average alpha.
“Don’t worry, that’s coming soon. I just have to prepare you first”, Kai goes through his stuff one last time, rut enhancers, lube, condoms, a box of latex gloves and lastly, a cock ring. He prepares a syringe, it’ll take some time for the effects to set in, might as well do it now.
“Hold still. For someone who pestered me for sex, you’re proving awfully unwilling”, he grabs one lanky elbow, piercing the skin with the needle and pressing down the plunger. Shigaraki lets out a hiss as its content is injected into his arm, “This wasn’t what I fucking meant!”, he snarls, trying to pull away but only getting so far. Kai disposes of the used syringe, preparing another one, this time for himself.
“Oh? Not what you expected? That’s a shame”, he rolls his shirtsleeve up, feeling around for a vein, annoyingly he has to use a tourniquet. Using his free hand and teeth to tighten it, finally finding a good one. He grunts as the serum burns through him, thirty minutes max, and they’ll both be experiencing a full blown rut.
“Don’t bother fighting it, just relax. It’ll be easier for you”, Kai grabs a bottle of lube, dribbling some onto his finger, rubbing them together and stepping closer to the bed.
Seeing the other alpha tense at his proximity, uncaringly he wraps his fingers around the mans soft cock. “Don’t touch me!”, Shigaraki tries to kick him away, but the bonds keeps his movements to a minimum, only managing to flail around like an idiot.
Kai picks up the small metal ring and begins to work the cock and balls through it, settling at the base. He begins to move his hand along the length, pulling back the foreskin, thumbing the head.
It’s almost too easy how fast it hardens, and soon enough Shigaraki is fully erect, beading at the tip. “What the fuck…”, Shigaraki mutters, Kai glances at the man’s face, its flushed and lips red bitten.
“Just enjoy it, alpha”, he mocks, his eyes crinkling derisively. “Fuck you!”, Shigaraki spits at him, but whimpers when Kai tightens his grip painfully in response. “Behave, mutt”, he lets go of the cock to dip down to the puckered hole, it clenches as he runs his fingers around it.
“Don’t! I don’t…I don’t want this!”, Shigaraki cries out, trying to flinch away, Kai snorts and starts pressing one finger inside. “You saw what I had prepared, then you let me tie you up and, you’re hard. Look at you, flushed, cock dripping. You want this, admit it”, he brings his freehand up to keep stroking Shigaraki’s cock, thrusting his finger slowly, adding another as the alpha groans at the stretch.
Soon he’s four fingers deep to the knuckle inside the man’s ass, he himself is sweating and whether it’s out of disgust or the serum taking effect, he doesn’t know. Shigaraki though, is certainly enjoying it, writhing and moaning.
Kai crooks his fingers upwards and a loud yelp comes out of the man, he does it again and Shigaraki thrashes on the bed, his cock leaking precum like a faucet. “Stop! Fuck! Stop it!”, teary red eyes look at him, begging, and Kai feels a twisted sense of enjoyment course through him. “No, I don’t think I will”, cruelly he digs his digits into the man’s prostate, pumping his cock fast, listening to the man’s cries.
Shigaraki lets out an anguished moan when he comes, inside clenching around his fingers and cock twitching, but nothing spills out. Dry cumming. Knot uselessly full, Kai almost feels a little sympathetic, it must be painful. He doesn’t stop at all, working the alpha through his orgasm mercilessly and into another.
The man looks disgusting, tears and drool running down his face, filthy. His own rut is setting in, his cock chubbing up at their combined scents of arousal. Kai supposes it’s time for the next step, pulling his fingers out and watching the hole wink at him, empty. Tossing the gloves and putting on a clean pair, undoing his own pants and pulling himself out, stroking himself to hardness.
Tearing open a packet of condoms, pinching the tip and rolling it over his length, making sure it’s properly secured. Positioning himself between Shigaraki’s spread legs and tuts when he tries to close them, putting his hands on each thigh to keep them apart.
“That won’t do, I’d advise you to relax”, he steadies his dick with one hand at the entrance, slowly he enters him, groaning at the tightness.
“Fuck! Fuck! Pull out! Pull out!”, the man beneath him screams. Kai catches the pained expression on Shigaraki’s face, he tries to soothe the man, stroking along his flanks. It’s getting awfully tight inside him, it feels like his dick is getting crushed, he wraps his hand back around Shigaraki’s flagging cock.
It perks back up fast with a little extra care, and Shigaraki is back to moaning like a whore. The man may say he hates it, but at this moment he’s no different than a fucking bitch in heat. Kai watches closely at the alphas every movement, twitching hands, slack-jawed and moaning, cock bobbing with his thrusts. Cute gloves though.
When Shigaraki had offered to take with him a pair of gloves, it had surprised him that the man would even bother to prepare something himself, subduing his own quirk no less.
“Fuck…”, he’s already close to his first orgasm, and Shigaraki on his way to his third, pushing in balls deep and stilling as his knot expands. A scream is torn out of Shigaraki as he’s stretched past his limits, “Fuck! Pull out! Fuck you! You fucking..-gah! It hurts!”.
Kai struggles to keep himself up as his orgasm crashes over him, rolling his hips as much as the knot lets him. He doesn’t really want to soothe the man, but the scent of burning grass makes his nose itch and skin crawl. Running his hands along the other alphas sides, shushing the mans whimpers as his knot softens enough to slip his cock out.
Tying off the condom and tossing it, he moves to check Shigaraki’s ass, it’s red and puffy but nothing serious. He’ll live. Rolling on another condom, he settles back between the lanky thighs, pushing in for round two. “Nnn…no…”, Shigaraki moans pitifully as he sinks back inside, but doesn’t fight him anymore, now that they’re both fully in rut it’ll only get easier.
He doesn’t know how many times they’ve fucked by now, lost count at the fifth or so round. Kai had to dress down halfway through, the heat getting to him, it should disgust him more than it does, being skin to skin against this vile creature. Foregoing even the mask as it stuck uncomfortably to his face, at least he still has his gloves. Though there’s one little problem even his rut riddled brain is aware off, Shigaraki’s hidden entrance has yet to open.
He had hoped he wouldn’t have had to, but if that’s what is needed, then… Kai pulls out even if they were both so close to their orgasm, pressing his fingers against the spot behind Shigaraki’s balls. Not yet. Pulling off his condom and thrusting back into the other alpha, making the man mewl. And it feels…entirely too good. “Shit, you’re still so fucking tight…”, he hisses as Shigaraki’s inside clenches around him, he grips the man’s hips.
They got rid of the binds a while back, leaving only the gloves as protection between them. The prime alpha may only look like skin and bones, but the view of his cock being swallowed by the pink puffy hole sure is hot. Shigaraki is ass up and face down on the bed, moaning incoherently and weakly thrusting his hips back.
Whining when Kai pushes inside one last time, knot tying them together as he cums inside, actually cums inside. He leans down to suck at Shigaraki’s swollen mating gland, feeling the man shudder as he licks and gnaws at the skin. Kai feels strangely relaxed wrapped around the other alpha, chest to back, how peculiar…
When his knot finally deflates enough to slip out he reaches down to touch the man’s taint once more, feeling a small slit. Nearly there. The feeling must be foreign to the other alpha, as Shigaraki flinches at his touch. “What the-what fuck is that?”, Kai moves off his back to let him up, but keeps running his finger up and down the slit.
“Stop that! What have you done to me?”, Shigaraki slaps his hand away and moves to touch the spot himself, looking visibly distressed when he feels it. Kai lifts an eyebrow, “You really don’t know?”. “Know what?”, Shigaraki takes on a defensive posture, flushed and covered in all kinds of bodily fluids he doesn’t look too dangerous.
Kai quirks his lips, leaning closer, “You thought prime alphas were simply bigger than the average alpha just for looks? No, it’s because you have a hidden secondary organ. A womb”. Kai moves to touch the man’s abdomen, fanning his fingers out, red eyes look at him distrusting.
“It’s a vestigial organ. Leftover from a time when there was a shortage of newborns. Though not many bother with making use of them in this day and age”, Shigaraki looks at him with an expression warring between disbelief and anger. “This wasn’t what we agreed on”, red eyes shine with silent fury, Kai clicks his tongue.
“No it was not explicitly stated, but I thought you knew. There’s a reason your inner alpha wasn’t fighting your submission. Don’t you want to experience it? If you don’t like it, I can just restore you afterwards”, Kai can see Shigaraki fight with himself, but it seems his curiosity wins over, he stifles a smirk. “Fine, but don’t try anything funny”, Shigaraki lies down on his back warily, Kai moves between his legs and gets back to work.
“I’d never”, he teases and starts rubbing through the slit again. It still needs a bit more persuasion, it’ll be easy enough to fix. He keeps rubbing the flesh, after a moment it opens up more and Shigaraki lets out a scared sound. Kai starts stroking the man’s cock again, making sure it’ll keep him relaxed.
His glove is getting wetter the more he touches, but it’s so slow, he’ll have to do something else. It’s not something he wants to do, but he moves to lay between Shigaraki’s legs, leaning his face up and licking a stripe through the folds. He hears a loud whine come from the other alpha, and does it again, “O-overhaul…”.
It unfurls prettily for his tongue, licking deeper for each pass until he can fit a finger inside, “It feels…it feels weird…”. Gentle strokes and lapping slowly, it tastes…kind of good. And Shigaraki starts thrusting back against his tongue and he delves it inside along with his finger, the alpha lets out a choked cry. Clear fluid spilling out against his tongue, coating his finger, Kai moans at the taste.
Cleaning up the slick and pulling away, wiping his face, his cock hard and curving upwards. He pumps it a couple times to alleviate the pressure, half-lidded eyes look down on Shigaraki’s flushed form, the man’s cock has kept a constant angry red color. The cock ring working better than he thought it would.
Before the alpha can protest, he positions himself at the newly opened vagina and pushes inside, he almost falls over from how good it feels. Wet, warm plush walls stretch around him. “A-alpha!”, Shigaraki creams around him, making him spill already, knot locking them together for what must be the dozenth time tonight.
Kai barely notices the gloved hands scratching at his back, doesn’t bother slapping them off as his orgasm hits him full force. From there on they both fuck like animals, Shigaraki looks like he has the time of his life, moaning and drooling.
He takes pity on the man’s cock, taking off one glove and disassembles the metal ring, Shigaraki cums instantly. Shooting semen all over himself in heavy spurts, and it leaves Kai feeling breathless as his dick is squeezed. Lasting a couple more thrusts before cumming again, they should probably be a little more worried about fucking raw, but that’s the furthest thing from his mind right now.
Distantly his mind is filled with thoughts about how good Shigaraki looks, how perfect his cunt feels, such a good fucking bitch. Stuffed to the brim with cock. The rut still thrums through their veins, they have all night and he’s going to make the most of it.
Kai wakes up an undetermined amount of time later, his whole body aching, sticky and disgusting.
It takes some time to take in his surroundings, they’re in one of his many safe houses, the air reeks. The normal musk of alpha rut, and something else, something sweeter. Shigaraki is still knocked out beside him, skin covered in bruises and marks, did he do that?
Looking down at himself, he’s not much better off, with a groan he moves to stand up, glancing back at the bed Shigaraki is dead to the world. He needs a shower, badly. Picking up his old clothes and throwing them into the washer, fetching a clean set to change into afterward. He almost boils off his skin to feel clean, scrubbing himself raw, and when he’s finally satisfied, exits the bathroom.
Shigaraki hasn’t moved an inch since he left, Kai fixes his tie absentmindedly while giving the room a once over. Messy, filthy, should be demolished. He studies the prime alphas sleeping face, it looks soft, even with its many scars. If you don’t like it, I can just restore you afterwards. That’s what he said wasn’t it? But what if he likes him like this?
He fits on his mask and jacket, slipping on his sneakers last. One final glance at the sleeping figure, and he’s gone. He might lose a safe house, but that’s a risk he’s willing to take. Maybe they can come to another agreement.
Kai struggles under the prime alpha, as his cock is ridden with manic fervor, letting out pitiful whimpers as he’s worked into overstimulation. Biting his lips when he cums again, it stopped feeling pleasurable a while ago, his poor knot expanding to lock them together once more. Red eyes look down at him, almost glowing with sadistic glee, “This is what you wanted wasn’t it, alpha?”.
Kai whines when Shigaraki starts moving his hips again, he-he can’t…no more… “Wanted to make me your bitch, well, look at you now. What a stud, such a-mmm…!”, Shigaraki cuts himself off with a moan as he hits that spot within himself, “Such a good stud for me, aren’t you?”. Shigaraki steadies himself with two hands on his chest, still mindful of keeping at least one finger on each hand raised. Kai can only try and flail with his useless stumps.
When he lost his arms, and had thought of Pops he was sure nothing could ever be worse, but this…this is hell. “I should thank you, this new cunt of mine. It has opened so many possibilities for me, I like it”, maniacal cackling fills his head as another climax is forced out of him.