Chapter Text
Katsuki leans forward in his chair, examining the small animal from its button nose to its green and white, fluffy tail. “What are you trying to say?”
“His condition is the effect of a quirk, Bakugo. There’s no telling how long he’ll remain in this form.” Recovery girl explains, placing a comforting hand on his arm.
On the exam table in front of them, the small rabbit’s nose twitches a mile a minute, taking in all the smells the sterile hospital room has to offer. The fluffy little omega doesn’t seem to have a care in the world, which, if Katsuki is honest, is a welcome change given the pressure he was typically under as a hero.
Speaking of.
Katsuki scoffs. “Still shit at dodging, huh Deku?” he asks the rabbit, who cocks his head in response, his long ears flopping to one side as he examines Katsuki with wide, curious eyes.
Shaking her head, Recovery Girl hands Katsuki a clipboard. “He doesn’t understand you. Not yet.”
Katsuki crosses his arms over his chest. “Well he’s still in there, ain’t he? He knows he fucked up.”
She sighs, probably lamenting all the trouble he and Deku caused her in the past— they were a real goddamn handful as teenagers— and passes him a pen. “Just sign at the bottom and you can take him home.”
“Hah?”
“He can’t care for himself, Bakugo. He’s just a rabbit.”
“Well I ain’t his damn mom. ‘S not my fault the idiot got quirked into a pom-pom.” Katsuki grumbles, shoving the paperwork back into her hands and moving to leave the room.
Just as Katsuki turns the doorknob, a strangled cry sounds from over his shoulder. When he turns around, he’s confronted with what might just be the cutest damn sight he’s seen in his life— not that he would admit ever admit it.
The freckled bunny is sitting back on his hind legs, his arms stretched toward Katsuki as he cries out. His little paws are grasping at the air between them as his eyes well up with tears. It’s entirely too cute and downright heart-breaking and Katsuki is beginning to think he got too soft on the nerd. The way his stomach twists tells him he can’t just fucking leave him here.
So he doesn’t.
A couple hours later, Katsuki is finally home, having spent more money on pet supplies for Deku than he ever did on shit for himself. One would think a rabbit would be a relatively low maintenance pet, and that is usually the case. But Deku isn’t just any rabbit— he’s an omega, requiring heat-control pills, nesting materials and a special diet to stay happy and healthy.
It turns out that, as long as he’s in this state, Deku requires a daily diet of leafy greens, so that’s what Katsuki gives him. He watches with curiosity as Deku’s fluffy little legs carry him across the kitchen tile, hopping along until he reaches his bowl.
Katsuki smirks. Even as a rabbit, Deku is a messy eater, tearing up bits of butter lettuce as he stuffs his mouth with leaves. He looks almost comical as he gazes gratefully at Katsuki, his furry, freckled cheeks puffed out like a chipmunk’s as he chews.
“Now ya like vegetables huh? Shoulda eaten them when you were human.” Katsuki chides, hoping for some kind of reaction to prove that Deku is really in there.
But the bunny is too occupied with his feast to pay Katsuki any mind; he might not even register his teasing at all. So Katsuki ignores the pit in his stomach, the little voice in the back of his mind telling him that this is forever. That his loudmouth hero partner will never annoy the shit out of him again, with his comments on quirk analysis and costume upgrades.
*****
Before Katsuki knows it, two weeks have passed since the incident, and he and his bunny have settled into somewhat of a routine.
Before he leaves for work each morning, Katsuki places Deku’s breakfast in his playpen. It takes up the better part of Katsuki’s living room, but it’s fucking worth it after he caught the bunny nibbling on his throw pillows and stinking-up his t-shirts.
He doesn’t know what exactly Deku gets up to during the day, but Katsuki is sure he’s happy enough. To the dismay of Katsuki’s bank account, he’s got hundreds of dollars of toys to chew on and armfuls of blankets and pillows to nest in, and the floor-to-ceiling windows offer a breathtaking view of the city sprawled below them.
In the evenings, Katsuki has taken to joining Deku in the play pen, sitting on the floor with him and playing one of his many favorite hero documentaries. At first, he was apprehensive about the rabbit's insistence on snuggling into his arms, but eventually he gave in. Now, the two are inseparable, Katsuki holding him close and smoothing his fingers through curly green fur as the rabbit squeaks in delight.
But sometimes, even in those moments when Katsuki is comfortable and warm, he misses the old Deku. He misses their banter, that spirited back and forth that ignited something in him. The old Deku inspired him to train harder, be better. He longed to see Katsuki reaching new heights both in his career and his personal life. But this bunny is only concerned with being held and coddled.
He always seems to fall asleep in Katsuki’s arms right when he’s planning to get up and go for a run, and Katsuki isn’t a monster. He can’t just wake up a sleeping bunny, his paws kicking and whiskers twitching as he dreams.
Anyone could get used to this lifestyle. And he does. Until one morning, when there’s no bunny waiting for him.
The gate of Deku’s spacious pen is wide-open. Inside, his pillows and toys are strewn around all over the place, as though a tornado had rolled through, his water bowl knocked over and wetting the carpet below.
An unfamiliar fear claws its way up Katsuki’s throat, strangling him. What the fuck? Where the fuck? He retraces his steps from the night before.
He closed the pen last night. He tucked Deku into his nest, for god’s sake— he had to detach the sleeping rabbit’s paws from his shirt, without waking him, lest he be subjected to Deku’s usual begging. The damn fluff ball never wanted to sleep in his own nest, preferring Katsuki’s bed.
He’s also pretty sure his bunny didn’t just gain opposable thumbs overnight…Did he?
Only one (easy) way to find out.
“Deku!” Katsuki shouts, hoping that in whatever form Deku resides, he remains as clingy as ever.
Sure enough, Deku bounces into the room from the kitchen, a bag of powdered donuts grasped in one paw, with sugar smeared over his cheeks and his fur. Katsuki should be angry, both at Deku for getting into Kirishima’s junk food stash, and at Kirishima for claiming a cabinet in Katsuki’s kitchen in the first place. But all he can think is Holy fuck.
This Deku is unlike anything he’s ever seen before, human or animal. He’s grown much larger than he was as a bunny, standing around five feet tall, about six inches shy of his human height. His white-tipped flop ears stand alert on either side of his head and a tuft of green fur on his chest is the only hair on his torso, the rest of it appearing fully human, along with his face, neck and upper arms.
Mossy green fur covers his forearms, which end in hand-like paws, dusted white with powdered sugar just like the rest of Deku. A trail of green hair leads downward from his belly button, to wide, furred hips and strong legs. Like his hands, his feet resemble the paws he had when he was in his rabbit form.
Katsuki doesn’t know what to say, so he settles for the simplest thing. “Deku?”
The rabbit’s nose wiggles in delight, a wide, familiar smile spreading across his face as he drops the bag of treats and launches himself into Katsuki’s arms. “Kacchan!” He cries, his arms in a vice grip around Katsuki’s abdomen as Deku rubs his face against his chest.
Katsuki humors him for a moment before prying the bunny off him to look him in the eye. “Are You fuckin’ fully back?”
Hopping from paw to paw with excitement, Deku exclaims, “Of course, Kacchan! Now I can finally sleep in your bed, right? I do love my nest, but you never let me keep your shirts in there and you smell so good. It’s so comforting, like this spicy-sweet scent that really—“
“Deku.” Katsuki interrupts, noticing the slight droop of the bunny’s ears as his mouth snaps shut. “Shit. Sorry. I just, uh. Since when do you give a shit about my scent?” he asks, running a hand through his hair.
Deku looks down towards the crumbs on the floor, his green ears laid back against his head in submission. “I, uh…Always?”
“Hah?”
A part of Katsuki knows that any omega would find an alpha’s scent alluring, given the right circumstances. But he never really considered Deku’s gender until recently. Sure, he knew the other was an omega, but none of that shit mattered when he was fighting his way to the top. Deku wasn’t a potential mate, he was competition— the only hero with a chance at showing Katsuki up.
And because the universe plays cruel jokes on Katsuki, he only now allows himself to see Izuku as an omega — when he’s in this ridiculous half-human, half-bunny form. Now, when he breathes in, all he can smell is a meadow after it rains. That refreshing scent belongs only to Deku. The one he rarely smells anymore, since the other began wearing scent-blocking patches to work.
They’re both blushing now, as Deku scrambles to come up with the right words. “Not in a weird way! Promise!”
“Uh-huh.” Katsuki says, stepping around Deku’s mess and into the kitchen. “You eating real food again now?” He rummages through the fridge, grabbing some vegetables just in case.
“I think so! Well, definitely more than lettuce.” Deku scoops the fallen donuts into their near empty-bag, and Katsuki has to stop him from returning them to the cabinet. He’s not about to let his—Hero partner? Pet? — eat off the damn floor.
True to his word, Deku stomachs a wider variety of food throughout the morning. He’s eating other vegetables now, and even bread. But just the sight of meat seems to make the bunny gag. Katsuki ends up going for a grocery run, dismantling the playpen and giving Deku free reign of his apartment until he returns— He did promise to watch Deku until he turns back into a human. That fucker isn’t about to poof back into full rabbit form on his watch.
But when Katsuki returns, his home is in disarray. No piece of furniture was spared. His couch cushions are ripped, the stuffing spilling out onto the carpet. Next to the sofa, the end table is chewed at the corners. Even Katsuki’s remote is worse for wear, with bite marks through the buttons. Katsuki is not excited to find out what destructive-as-fuck form Deku has shifted into now, but someone’s gotta answer for this shit— and pay for it, hopefully.
Taking a deep breath, Katsuki shouts, “Deku! I’m home!” Immediately, the omega hybrid pops his head out from what appears to be a pile of laundry on the kitchen floor, only for his eyes to widen at Katsuki’s angry expression before he darts beneath the towels again with a high-pitched yelp.
“Deku.” Katsuki prompts. Deku doesn’t respond, choosing to remain in his hiding spot, so Katsuki tries again. “What the fuck, Deku?”
The pile of laundry is vibrating now, and it takes a moment to realize Deku is shaking. Maybe rabbit hybrids are as skittish as regular-ass bunnies. Katsuki has no idea, because up until today, he didn’t know such a creature could even exist. But if he’s right, he’s going to have to switch gears.
Katsuki takes a moment to do the deep breathing exercise his therapist taught him— in through the nose, out through the mouth. And soon, he’s calmed down enough that he thinks he can speak without scaring the fluffy omega.
“I ain’t mad, Deku.”
The towels shift, and Katsuki takes that as evidence that Deku is listening. So far, so good. He clears his throat. “I’m going to clean up, okay?”
The towels do not respond.
“I’ll be in the living room when you’re ready to talk.” Katsuki says, using every bit of his willpower to avoid making any sudden movements, yelling, or exploding Deku out of the damn laundry.
This time, he doesn’t stick around long enough to discern the bunny’s reaction, opting to focus on the wreck that was once his living room. It turns out that the mess had initially looked a lot worse than it is—he will definitely have to replace his end table, but most everything else is salvageable. So he orders delivery for the first time in god knows how long, and sets the food on the coffee table, sitting back against the torn couch cushions.
He hears muffled sounds from the kitchen, and spots Deku standing at the threshold between the two rooms, his ears back against his head and nose twitching furiously. He fiddles with his hands, but Katsuki knows he hasn’t eaten since he returned. It’s been hours.
Patting the seat next to him, Katsuki calls Deku over, and the bunny approaches cautiously, finally seating himself at the other end of the couch from Katsuki. He slides a takeout container across the table, careful not to startle the omega, who looks to Katsuki, reluctant to accept the offering.
“It’s vegetarian.” Katsuki clarifies, as calmly as he can. Deku nods and takes a timid bite, closing his eyes and savoring the flavor, and soon his tail is wiggling happily in spite of his overall demeanor.
“Look, I’m sorry for yelling. It’s just that I fuckin’—“
Deku silences him with a gentle paw on his shoulder. “That’s not it, Kacchan.”
“What are you so upset for then?” Katsuki asks, dumbfounded.
Looking down, Deku pushes his food around with his chopsticks as he conjures a response. His freckled cheeks are dusted with a rosy blush, and for a second, he looks like his old self. The Deku who could do anything, be anything he wanted. Not even quirklessness kept him from his goals.
Deku glances back up, his green eyes meeting Katsuki’s own. “While you were at the store, I tried to summon One For All.” he admits, placing his takeout container down on the table in front of them and turning toward Katsuki. His voice quivers. “It’s gone.”
Katsuki’s eyes widen. “The hell do you mean it’s gone?”
“I don’t feel them anymore. The other users.” Deku fiddles with his floppy ears. “I couldn’t even summon one percent. That’s why I got so anxious and, well…” he gestures to the gnawed-on end table.
As much as Katsuki hates to admit it, Deku’s bunny instincts seem to be intact. He’s not fully himself again yet, no matter how lucid he is, and no one is more aware of the fact than Deku. Katsuki’s alpha doesn’t give him long to dwell on the problem though, as every cell in his body screams at him to comfort the omega in distress.
Katsuki grits his teeth, releasing the most calming pheromones he can muster, given the circumstances. It’s not a perfect fix, but a glassy-eyed, high-as-a-kite bunny is better than one on the verge of a midlife crisis at twenty-three. They’ll continue the conversation later, Katsuki decides, wrapping the omega in a warm blanket and scooping him up. He adjusts Deku in his lap to ensure that the other gets the full effect of the calming smell, his nose tickling Katsuki’s scent gland.
Deku sighs appreciatively, clutching Katsuki’s shirt in one warm paw and nuzzling into his neck. It’s so strange to have Deku of all people in his lap like this, especially in this hybrid state. But something about the domesticity is soothing and familiar, and his alpha rewards him with endorphins the closer he is to the other. So he closes his eyes and gives in to the feeling.
*****
It takes Izuku a moment to realize the source of sound coming from the other room. Untangling himself from Kacchan’s sleeping form, he quietly approached the door, swinging it open to reveal none other than Kirishima, who was eating a lollipop before it dropped out of his mouth and onto the floor.
“Dude…” Kirishima says, wide-eyed, reaching to feel one of Izuku’s lop ears. “Shit, you’re a mutant now? Bakubro never tells me anything.” Kirishima is scratching between his ears now, and Izuku can’t help the way he squeaks as his paw thumps against the floor in delight.
“I— Izuku starts, only to be interrupted by an arm around his middle, yanking him back against a muscled chest. The spicy scent of cinnamon wafts over them, stronger and sweeter than usual. It dominates all other smells, the experience similar to walking past a Cinnabon at the mall. Izuku does the best to ignore it and preserve his higher brain function.
The hold on him tightens, and Izuku wills himself to think uncomfortable thoughts— anything to prevent slick from accumulating in his fur. Shigaraki’s face. Failing an exam. Poorly-made katsudon. Rotten eggs. Kacchan’s muscles. Shit, that last one was hot. Stop it, brain!
“What’re you doing here, shitty hair?” Kacchan growls. Izuku can feel the nose pressed into his hair wrinkle in disgust, as though the scent of the other alpha is personally offensive. It doesn’t bother Izuku at all though— Unlike Kacchan, Kirishima wears scent-blocking patches, and the one on his neck now has dulled his black cherry scent to a pleasant smell, akin in strength to that of hand soap. It clashes with Kacchan’s overpowering scent, but it’s familiar and welcome enough.
Kirishima holds up a paper bag. “I brought breakfast!” he grins, crossing the threshold into Kacchan’s apartment. Soon, they’re settled at the kitchen table, and Kacchan has thoroughly explained the situation, from the moment the villain turned Izuku into a rabbit, to the loss of his quirk.
Across from the two of them, Kirishima takes a bite of his sashimi, chewing thoughtfully. “I don’t get it though, man. Why is he naked?”
“Hah?” Kacchan exclaims, looking down at the bunny before forcing his gaze upwards, the tips of his ears reddening. The sugary smell is stronger now and Izuku is beginning to suspect it’s a sign of embarrassment.
“Don’t worry, Kirishima! I’ve got plenty of fur, so I’m not cold at all. See?” Izuku moves to stand but is quickly pushed back into his seat by his shoulders. The scowl on Kacchan’s face tells him not to press the issue, but he can’t help himself. “Hey!”
“He’s got a point, idiot! You aren’t wearing pants!” Kacchan argues, the flush spreading down from his ears, past the collar of his shirt. Izuku can practically taste the cinnamon sugar on his tongue now, it permeates the air so strongly. He needs to embarrass Kacchan more often, he muses, his body heating in response to the scent as warmth pools low in his abdomen, just a drop of slick escaping him.
It’s not much at all, but the other two have definitely noticed. Kirishima’s eyebrows are drawn together, and Kacchan’s face is even redder than before as the cinnamon sugar scent intoxicates Izuku. The bunny hums, swaying to music that exists only in his head, and before he knows it, Kirishima has gone and Izuku is being bodily thrown into his nest of towels, before Kacchan storms out of the room.
“Kacchan?” Izuku calls after him. But there’s no response. When he doesn’t return after a few minutes, Izuku elects to go find him. Knocking on his bedroom door, the bunny prompts him again. “Are you okay, Kacchan?”
“Just go away, Deku!”
Izuku’s tail droops, his ears flattening against his head as his stomach twists. Did he do something wrong? Tentatively, he pushes the door open. But the image before him brings him to pull it shut almost immediately. “Eep!” Izuku yelps, hopping back.
Izuku can hardly think— his brain has been turned to complete mush by the sight of Kacchan…like that.
Kacchan was sitting at the end of his bed, his strong thighs spread to show off the impressive cock in his hand. Boy was it big— so, so much longer and thicker than Izuku’s own, and flushed a deep pink from root to leaking tip. He can’t bring himself to be embarrassed, having walked in on the gorgeous alpha stroking that deliciously hard length, glistening with what Izuku can only assume is artificial slick. Holy shit.
It’s all coming together now. Kacchan’s unusual aggression towards Kirishima, his possessiveness of Izuku and that thick, sweet scent of cinnamon rolls fresh out of the oven. Kacchan is in rut. Kacchan is in rut, and Izuku has to live here with him until he’s human again. That could take weeks! How is he supposed to suppress his urges that long, when the object of his affection is mere feet away, thrusting into his own hand?
Not that Izuku doesn’t want to help him out, but he’s barely a person, if he can even call himself one. Sure, there are others in society who have some animal anatomy, but to Izuku’s knowledge, they aren’t at the mercy of animal instincts. He barely stopped himself from munching on the plastic grass that garnished the sushi container this morning! He’s startled by the slightest noises! And to make matters worse, Izuku’s sexual urges are stronger than ever as well, his omega urging him to fuck, mate, and breed.
Slick dripping down his inner thighs, his smaller cock hardens from the sounds of Kacchan’s desperate moans. Izuku is beginning to regret spitting out all those bitter tablets Kacchan had snuck into his rabbit food. They must have been heat-blockers. Of course they were! But when he was just a fluffy little bunny, his omega wanted to cuddle with Kacchan and eat butter lettuce, and pills didn’t fit into that carefree lifestyle. The fever that began earlier is only intensifying, a fire consuming him from the inside.
There’s no doubt about it— Izuku is in heat, with a rutting alpha in the next room.