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Bunny Business

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It happens on the first day of patrol. Not the first day of patrol in a new agency, or in a new year, or anything like that, no. It happens on their very first patrol as pro heroes


Deku and he are Miruko’s sidekicks, on one condition: that they work together.

( “The two of you are two halves of one whole: either I take both, or neither.” )


And saying no to that offer would be fucking ridiculous , so here they are, getting dressed on their first day. Katsuki would never ever admit it out loud, but he’s nervous . He has every right to be; it’s his first time out as a proper pro, and with Deku nonetheless. 


This is an issue for several reasons. 


Deku, unlike what Katsuki had expected, doesn’t look fucking nervous at all (and he knows when Deku’s nervous; he’s never been good at hiding his expressions and emotions, something that he’s gone from hating to finding endearing, ugh). 


The second issue is the fact that they’re adults now. Deku isn’t the wimpy little kid he used to be, and neither is he the person who always breaks his bones, pushing himself too far and getting taken out of the game. No, Deku’s a fully fledged pro, and whilst he might be as short as ever, his muscles are more defined (his curves are more defined), his temperament is cooler, and he’s hella more confident. It’s a good thing, obviously, but when they’re patrolling together, Katsuki’s gonna have to make sure that the nerd doesn’t end up outshining him.

If that isn’t enough, then there’s Deku himself. Forget him being a rival, he’s a fucking distraction , a sun so bright that Katsuki can’t help but stare. Deku’s fucking amazing, he admits that much now, and every time Deku isn’t looking, Katsuki’s eyes are on him. He’s inimitable, and Katsuki is, in a word, fucking whipped (fucking doesn’t count as a word, clearly). 


So there they are, changing, and Katsuki almost puts his gauntlet on backwards because he keeps sneaking glances at Deku. Deku’s everything he’s ever wanted, and Katsuki’s at peace with it, but telling Deku is a whole separate ordeal. He was going to confess at the end of their third year and then leave, whether or not Deku accepted him, but now? They’re a fucking duo, what the hell is he meant to do!? 


He can’t ruin their work relationship, after all.

They make it out onto the streets after a pep talk from Miruko—at least, it was meant to be a pep talk, but Katsuki’s gone from thinking he’ll accidentally letting a perp escape, or look dumb in front of Deku, to being fucking terrifed that he’s gonna end up on national television for fucking everything up. Of course, Deku being Deku, notices Katsuki’s mood, and tries to cheer him up as they start down their second street, perfectly in sync with each other.

“Kacchan—oh uh, I mean, Dynamight —don’t worry!” Izuku says cheerfully, patting him on the back. And fuck, Deku might be small, but he’s powerful. Katsuki, even at the six foot one he now stands at due to puberty, feels himself lurch forward ever-so-slightly from the force of Izuku’s ‘pats’. “You’re an awesome hero, and you’re not alone! We’ve got each other’s backs, remember. What was it that All Might said? Save to win, and…?”

“Win to save,” Katsuki grumbles, rolling his eyes as he finishes what is practically their slogan now. 


But he can’t help the light smile that plays on his face.

“Oh, that reminds me, Kacchan, I had a few ideas for us! I know we’re not an proper duo yet, a-and I’m not saying that we’ll definitely be a duo, but we’re debuting as a sidekick duo, so I was thinking—”

Izuku’s so busy rambling, and Katsuki’s so busy fawning over him ramble, that neither of them notice when they turn the corner and a middle-aged woman bumps into them, yelping as she falls. Luckily, Izuku catches her, concern flashing in his eyes.

“Ma’am, I’m so sorry!” he exclaims, cradling her in his arms as she blinks up at him. “A-Are you alright? Can we get you any help? We should really watch where we’re going, we’re so sorry!”

She smiles up at him, her lips pulled a little too tight.

“I’m just fine, dearie, don’t worry—it was my fault entirely, I was in such a rush!” Her tight-lipped smile turns into a full frown as she glances him over. “In fact, I should be the one apologising. I may have activated my Quirk on you in my surprise. It takes a while to kick in, and only lasts for a few hours, so I won’t have inconvenienced you for long , but I’d suggest your partner take you back to your agency as fast as you can and see if there are any effects. If there are, give me a ring on this number for more information, and try not to exert yourself too much—it can be quite difficult to adjust to! Oh, but you should be fine. Anyway, I must dash, I’m ever so sorry!”

She thrusts a business card in Katsuki’s hands and hops up out of Deku’s arms, scurrying away rather suspiciously.

“Shouldn’t we like, take her in for Quirk misuse?” Katsuki says, watching after her before turning to Deku. “She might have hit you with something dangerous.”

Deku shakes his head.

“She might not have affected me with her Quirk at all, and if I have been hit, we always have her business card to track her down,” Deku smiles, brushing himself off. “Anyway, Kacc— Dynamight , I think you should escort me back to the agency, don’t you?”

It’s a completely innocent statement, but something about the way Deku’s eyes sparkle makes him blush as he stutters out, “Y-yeah, whatever,” and starts walking without warning. Deku laughs and catches up to him easily, peering up at him from his small height as they walk back.

“Kacchan, why are you so red?” Deku asks, causing Katsuki to blush even fucking harder. Fuck , he hates Deku and his stupid unnecessary charm. Why the hell does the nerd have to make him feel so fucking warm and gooey and shit?


(And that’s not even mentioning the lust —)

“Stop fucking asking about me, you might’ve been hit by a fucking Quirk!” Katsuki snaps, walking faster (Deku still manages to keep up with him, the speedy little shit).


“Aww, Kacchan cares about me!” Deku grins, practically bouncing up and down. It’s weird how bubbly he is, almost more than usual, but it’s whatever—as long he gets him back to the agency, they’ll be fine .


Only, as soon as they step foot in the agency, Miruko—standing in the lobby to confirm a few details with the receptionist—immediately whips her head around, practically charging at them. She grabs Deku by the chin, tilting his head this way and that with concern apparent in her eyes.

“What Quirk have you been hit with?” she mutters, before turning to Katsuki. “What Quirk has he been hit with!?”

“There—There was this lady, uh, she fucking crashed into him and then said that she might have hit him with her Quirk accidentally but she didn’t know so she just gave us her business card and fucking bolted after telling us to bring him back to the agency just in case,” Katsuki summarises quickly, handing the business card over to her.

“Let me get this straight—a civilian might have mishandled their Quirk, and you just let them go ?” Miruko asks, cocking an eyebrow disapprovingly.


“It was my fault!” Deku says, squirming a little in Miruko’s grasp as he hops from side to side. “Kacchan wanted to go after her, but I-I just thought it would be better to get back to the agency in case it was serious, so—”

“You can explain yourselves later,” Miruko cuts in, stepping away and wrinkling her nose. “Dynamight, get Deku to a spare room, lock him in, and then leave as quickly as possible. Do not linger unless you want him to—Look, just take him someplace safe, now . We’re gonna track this lady down. Deku’s your responsibility.”

“B-But I’m fine !” Deku insists, still full of energy. He scratches at his head, before moving to the small of his back. “Okay, well, I feel a little weird, but I don’t need to be locked up— wahhh !”

Katsuki doesn’t have time for Deku’s excuses, not when their boss is glaring at the pair of them like that . They’re a fucking team, so when they fuck up, they fuck up together, and hell if Katsuki’s earning bad points from Miruko just because Deku’s an idiot. He lifts him up, slinging him over his shoulder (trying very hard not to think of how Deku’s abundant ass is pressed against his cheek) and carrying him to the lifts. 


Deku whines and kicks, insisting that he can at least walk by himself, but Katsuki’s having none of it. He has his orders, he has to listen to them. But whilst they’re in the lift (to get to the top floor—mostly empty offices, no one to disturb Deku), Deku starts squirming in earnest.


He activates OFA and darts out of his grasp, so fast that Katsuki can barely react, but when he goes to grab Deku, the hero drops to his knees, clutching his head and his tail. 




His what now?


At the base of Deku’s back, there’s a fluffy bunny tail, matching Miruko’s. When he looks back up at Deku, long floppy bunny ears have sprouted, nestled on either side of his face as they flop over his ears.

“Deku, are you—” Katsuki tries.


Deku’s ears perk straight up (his—his bunny ears , not his human ones), and Katsuki doesn’t even make it through the whole sentence before Deku whimpers: “K-Kacchan, you really need to get me to that room.” 


When the lift doors open, Katsuki doesn’t waste a second in taking Deku by his plush hips and rushing him to the first empty room. Once he’s checked that Deku’s okay, he’ll lock the door and give him the space Miruko thinks he needs, but as soon Katsuki sets Deku down, Deku pounces on him, knocking him to the ground.

“D-Deku, what the— Fuck , Deku, what are you doing!?” Katsuki exclaims. Because Deku’s not just sat on top of him, no. He’s grinding his big ass over Katsuki’s rapidly hardening dick, tugging on his own ears as he moans.

“N-Need K-Kacchan t-to breed me,” Deku says breathlessly. Oh . The nerd’s in fucking heat . When Miruko said lock him in and leave , this was what she fucking meant. 


Katsuki glances at the door, wondering if he could somehow escape in time, but Deku must catch the movement, because he pushes his heavy ass down further against Katsuki’s erection, eyes flashing green as he says, “Kacchan, you’re not going anywhere . Y-You’re gonna breed me, aren’t you, g-gonna fuck me and fill me up? I neeeed it, Kacchan!”

Katsuki’s breath catches in his throat. What the fuck does he do ? Tell Deku that he can’t do shit without his explicit permission, and that a heat-crazed hero hit by some sort of twisted bunny quirk can’t give consent? No, because he knows that Deku won’t fucking accept that in a state like this. If he leaves, he’s putting Deku in danger of god knows what, but if he stays

Apparently he’s taking too long to make a decision, so Deku makes it for him. He rises on his haunches, tail twitching as he leans forward a little—

And, with a resounding tearing sound, rips right through his own hero costume. Katsuki’s betraying his lust in his eyes, because Deku grins (and oh fuck , if the feisty grin isn’t the hottest damn shit he’s ever seen, what is ?) and turns around seductively, presenting his naked, overspilling ass as he straddles Katsuki’s cock backwards. Or well, almost naked, though the way his generous ass swallows his underwear doesn’t leave much to the imagination. But most of all, Katsuki’s caught off guard by the way actual slick wets his thick thighs as he pushes his underwear down over his ass.


“Deku, y-you can’t—” Katsuki manages, trying to avert his gaze from the whole fucking meal in front of him. His dick strains against his trousers, aching as Deku rubs his shiny, round ass over it tantalisingly, the fluffy bunny tail somehow adding to his appeal. Fuck, he wants it, wants to spank Deku and watch him take his fucking cock, but he can’t afford that, because Deku’s— Deku’s not thinking right.

“Mmm, Kacchan, I-I know you want it,” Deku giggles shamelessly, reaching back to unzip Katsuki’s trousers slowly. He holds his gaze, and Katsuki knows that this is where he should grip his wrist and say ‘ enough ’, but the command doesn’t leave his lips. He just swallows, watching as Deku pulls out his thick, hard length and groaning low in his throat when Deku starts to stroke it slowly.

“F-Fuck, Deku—”

“You want me to bounce on your long , h-hard cock, Kacchaaan ?” Deku purrs, biting his plump lower lip as he presses Katsuki’s dick between his big ass cheeks, slicking it up with his wetness. The tip of it grazes Deku’s tight hole a few times, and both of them moan softly in sync. Then, Deku lifts himself once more, and Katsuki gets a moment to admire the view before Deku grips Katsuki’s dick with purpose and slams down on it, bottoming out in one go as his ass jiggles from the impact. Katsuki’s hands fly to Deku’s body as a loud, drawn-out sound escapes his lips. Deku pants heavily as he wiggles his ass, getting adjusted to Katsuki’s size. Then, without hesitating, he starts to bounce on Katsuki’s dick, powerful thighs moving up and down and up and down rapidly as he fucks himself on Katsuki’s thick length.

Katsuki fucking helps him, one hand squeezing his fat ass and the other gripping a long ear as he thrusts up into Deku’s tight heat. Fuck, he sounds and feels so much fucking better than he could’ve ever imagined, and as Deku looks back, Katsuki knows he’s in love (as if he didn’t already, fuck ). Deku’s eyes roll back, mouth open as his tongue lolls out helplessly when Katsuki tugs on his ear and switches to a deeper angle.


Yessss, Kacchan, mmm, so big and thick and perfect for me, Kacchaaaan,” Deku moans loudly, so vocal that Katsuki’s relieved that the floor is mostly empty. “Ohhhh, want you to—ohhhh, yes yes yes, harder!—w-want you to fill me up and breed me, Kacchan, please!”

“Fuck, yeah, gonna fill you up so fucking good , bunny, gonna fuck your fat, slutty ass over and over and over ,” Katsuki growls, all inhibitions gone as he rams into Deku’s prostate relentlessly, bringing them both closer to tipping over the edge as they fuck at a merciless speed. Filthy sounds fill the air, and Katsuki knows that he’s not gonna last much longer.

K-K-Kacchan , go-gonna, gonna— ohhhh —I-I’m gonna—” Deku gasps out, so Katsuki yanks at his ear and drives in harder as a rough hand comes down to slap Deku’s big, round ass. Deku screams, bouncing faster and faster as he cums all over Katsuki’s thighs. The sensation of Deku’s hole clenching around him, the sight of his ass jiggling against his body as his tail twitches, the sound of Deku fucking screaming his name —he can’t fucking help himself . Katsuki arches up against Deku as he orgasms, spilling deep inside him and filling his dripping hole with his cum until Deku’s fucking leaking .

They collapse against each other, breathing heavily. Katsuki doesn’t want to think about what they’ve done for now, content to just rest against him and bury his nose in Deku’s hair. But it seems like Deku has other ideas, because after a few minutes, he moves to murmur, “Kacchan, do you wanna fuck your little bunny again?” against his lips.

And who’s Katsuki to say no?



It takes a few hours for the Quirk to fade, and by the time it’s truly worn off, the two of them in Miruko’s office in their civilian clothes (that one of her assistants had kindly brought up to them), the embarrassment starts to kick in. Miruko doesn’t say much about what they’ve actually done , debriefing them on the Quirk and leaving them to talk things through with a very pointed look.

“Kacchan, I—”

“I’m sorry for fucking you without your consent,” Katsuki blurts out, because he’s fucking stupid . Deku flushes bright red, fidgeting with his fingers.

“I’m the one who should be apologising, I forced myself on you,” Deku says awkwardly, not meeting Katsuki’s gaze. Katsuki shuffles his chair closer so that he can take Deku’s hands in his. That captures Deku’s attention at last, and Katsuki takes a deep breath before saying:

“I wanted to. I’ve been thinking about you for fuck knows how many years. I didn’t know how to fucking tell you, but—”

“I like you too,” Deku says for the both of them, bringing all of Katsuki’s gears to a screeching halt. Deku’s eyes widen when Katsuki freezes, and he flails about (even with their hands still intertwined). “Th-That was what you were gonna say, right!? D-Did I read it wrong!? Oh god , I’m so sorry, I—”


They’ve been interrupting each other all day, they’re always interrupting each other, but Katsuki’s never been more happy to interrupt him than now, pulling Deku close and claiming his soft lips with his own. 


“Nah, you got it right,” he whispers, drawing back a little. “I like you a hell of a lot.”

Deku beams at him, and replies: “In that case, I might hop in joy.”

Katsuki rolls his eyes affectionately as Deku giggles at his own joke and pulls Katsuki back in for another kiss. The two melt against each other— just the way it should be , Katsuki thinks.