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Time travel is a bitch.

Bakugou’s long since learned to try and ignore any philosophical and physical repercussions of it, and his missions are mostly seamless; that doesn’t mean, however, that he’s not profoundly annoyed when Deku knocks on his office door reminding him about Warp, a low-level villain climbing up the ranks by sending local heroes back in time and doing his deed while they’re gone.

Him, Deku and the rest of the agency—mostly comprised of former 1-A students—had been on the lookout for enough time to know Warp’s limits; he can’t affect more than one person at once, and Bakugou had been assigned to take the hit for the team while they arrest him. (Because Deku’s an asshole who loves taking advantage of Bakugou’s newfound tolerance for teamwork.)

He’s known about it for a few weeks, and everything goes according to plan. But when Bakugou wakes up in a dark alley in Mihama ward, with no idea of what to do or even how far back he’s been transported, he reluctantly admits to himself he’s disoriented.

*

There are way too many parks around. Bakugou can’t stand the loud kids screaming and occasionally running past the bench he’s hoarded, but he’s got no idea where the nearest cheap hotel is, and he’s not about to take the half hour train ride to Tokyo either. Bakugou isn’t a time travel expert; he doesn’t know any potential consequences of staying near home and running into a past version of himself, and he doesn’t want to risk it.

He’s convinced this is God’s way to punish him for whatever bad deeds he’s done in the past.

He sits in silence with his arms crossed, too afraid to use his phone in case anyone gets suspicious. He’s already attracting unwanted attention, what with the—toned down from his UA days, but still explosive—flashy hero costume, and he really doesn’t want to complicate this any further.

However, any concern for concealing his antics go flying off the window when he spots a group of boys, apparently play fighting to test their Quirks in a dark alley across from him. He doesn’t usually get on people’s backs for petty things like unregulated Quirk usage. That’s Iida’s thing, the lawful bastard. But he’s so bored, and his body aches for some kind of action, and okay, maybe he wants to yell at rowdy teenagers. It’s cathartic.

He jogs over to the kids, setting off small, warning explosions. “Hey, you three!” Bakugou calls out. “What the fuck do you think you’re doing?”

Two of the boys whisper between themselves, likely questioning Bakugou’s identity, before turning around and dashing away from him, into a strange maze of streets he doesn’t recognise.

Bakugou sighs. He doesn’t care enough to go after them, anyway, and his status as an unknown, still unregistered hero, despite the licence on his pocket, wouldn’t let him go very far anyway. He settles for interrogating the kid who stayed behind.
“Why didn’t you run off too, dammit,” Bakugou says. “You suck at being a delinquent. Who are you, anyway?”

The boy doesn’t answer. Bakugou scans his face—he’s frozen and staring straight at Bakugou’s abs, unmoving except for the heaving of his chest. It’s understandable, being scared in a situation like this. Kid doesn’t look older than a middle school student, anyway. Probably thinks he’s going to be locked up for the rest of his life.

But he hasn’t got the patience to coddle a messy teenager, not really. Bakugou snaps his fingers in front of his face. “Hey, cat got your tongue? I asked you your fucking name,” he tries again.

“Kirishima Eijirou,” the boy sighs, looking down.

Bakugou gapes. It all comes to him in a flash: Ashido’s teasing, the shitty class pictures, old shots of Kirishima drooling during school, things she’d collected over the years of middle school and used to blackmail Kirishima.

“Eijirou? Are you—are you fucking kidding me?”

“What?” Kirishima stammers, his voice cracking, and oh God. “Do you know Ma? Dammit, don’t tell her, okay?! I tagged along because they kind of made fun of me, and, and I had to! Haven’t you ever been a kid before, man? We do stupid shit all the time!”

“No, no, no, oh my fucking God. You’re Eijirou. Kirishima Eijirou? Like, Crimson Riot fan? Holy mother of fuck,” Bakugou almost yells.

Kirishima’s eyes widen. “How do you know me?! I’ve never—I’ve never even seen you around!”

And, technically, this is supposed to be a secret. Yaoyorozu, with her pretentious scientist flair, has warned him a billion times about the weird ramifications of time travel and butterfly effect or whatever. Bakugou isn’t supposed to share details of his mission, or even mention he’s on a mission at all.

But when he realises a ten years younger version of his fiancé has been ogling him since he came into view, and said teenage fiancé is giving Bakugou terrified puppy eyes he’s never learned to resist—he feels he owes Kirishima an explanation.

*

“So you’re… My friend. From the future,” Kirishima repeats for the hundredth time. And for the hundredth time, Bakugou doesn’t mention they’re something more, because who knows if this Kirishima’s had his weird Crimson Riot-related sexual awakening yet. He sounds slightly sceptical, but in face of Bakugou’s hard proof—his cell phone and hero licence—there’s not a lot of room for denial.

“Is it so hard to understand, shithead,” Bakugou grunts, still staring out the window. He doesn’t even get to call Kirishima shitty hair, because his natural black bangs are… Kind of charming. Dorky, because he’s in middle school, but definitely a good look on him. “Also, stop staring at my goddamn chest.”

Kirishima chokes and has the decency to look ashamed. “I… I’m sorry. I don’t know what came over me… Ground Zero, sir, uh.”

Bakugou sighs and tries not to show how Kirishima’s different, more respectful, treatment affects him. He thinks that wanting to ravage this middle school student is objectively kind of creepy. He also thinks it doesn’t really matter, because he’s already fucked and been fucked by Kirishima anyway. But that’s getting too much into the philosophical side of things, which he knows to avoid at all costs.

“It’s just,” Kirishima continues, and Bakugou raises an eyebrow at him. God, Kirishima looks good, the red of the sunset bleeding into his tan skin and lighting up his eyes. “It’s been kinda weird, these past weeks. And all of a sudden someone from the future shows up and it’s almost like the universe is trying to tell me something, y’know?”

Bakugou feels bolder, watching the way Kirishima looks up at him with a tinge of admiration but also something else, something he wants to unravel and feel for himself. “Maybe it’s trying to tell you to accept things you’ve already known for a while,” he says, stepping just a little closer.

They’re all alone, in this cheap hotel room near the Chiba station so they could discuss Bakugou’s situation in private, and he wants.

He wants to take this younger, lost Kirishima between four walls and find out what he looks like when he’s moaning into a pillow. He wants to destroy the room and stain the patterned sheets, and he wants to swallow Kirishima whole. The consequences don’t matter to Bakugou, because he’s going to go back to his actual life soon, anyway, and Yaoyorozu’s harsh warnings don’t even come to mind.

It’s reckless, but Ground Zero has never been known for being careful.

Bakugou doesn’t have to make the first move. Kirishima gets on the very tip of his toes and wraps his arms around Bakugou’s neck, clumsily leaning in so he can finally, finally taste. The kiss reminds him of when they started dating, in his actual timeline, Kirishima’s sharp teeth wreaking havoc on Bakugou’s already chapped lips.

Bakugou’s experience gives him an obvious upper hand. He’s ballsy enough to run his hands—God, they're so broad against Kirishima’s tiny, unsculpted body—down his sides, feeling him up and eventually stopping to squeeze his ass, dragging a gasp out of Kirishima.

And Bakugou whispers against his ear, “jump.”

Kirishima obeys. Bakugou hoists him up with ease, allowing Kirishima to wrap his lanky legs around Bakugou’s waist. It makes it much, much easier to get the both of them against a wall, pinning Kirishima so he’s even more helpless.

Instead of resistance, Bakugou is met with glee. Kirishima unabashedly stares at the broad expanse of his shoulders, the way his muscles shift every time he moves, and Bakugou thinks he’s never seen a teenager this horny in his life.

“Ground Zero,” Kirishima says, in a breathy voice that makes Bakugou grind against him like he’s a needy high schooler once more.

“Katsuki,” Bakugou says, all inhibitions long gone from seeing Kirishima moan and gasp like it’s nobody’s business. “You can call me that.”

Kirishima runs a hand down Bakugou’s chest, over the tight fabric of his hero costume that accentuates his muscles. Bakugou smirks. This Kirishima hasn’t gotten a chance to bulk up yet, to become the strong hero Bakugou knows he’s always wanted to be, and he gazes at Bakugou’s body like it's some kind of unattainable perfection. “I probably already do, don’t I? Back in your… Future. I guess. Man, this is weird.”

“Fuck yeah you do,” Bakugou breathes, their lips almost touching. “And there’s not a single goddamn timeline where it doesn’t get me going.”

He kisses Kirishima again, stronger this time, and goes down, down, down, sucking at his neck just above where the school shirt covers it, and he’s taken by a need to mark Kirishima up. “I want to bruise every fucking inch of your skin,” he breathes, kissing over the bite marks.

Kirishima whines so loud at his words Bakugou worries they’ll get caught. He looks down to notice a bulge straining under Kirishima’s uniform. “Fucking teenagers,” he says, but makes a move to unbutton Kirishima’s pants anyway. “How fucking old are you, anyway?”

“Thirteen,” Kirishima whispers, like it’s some kind of secret—and with what they’re doing, it really, really has to be. “But I’m fourteen next week?”

Bakugou swears and busies himself with sliding Kirishima’s trousers down, if only to keep himself from going mad. Kirishima looks up at him with half-lidded eyes, barely covered by his messy bangs. He mirrors Bakugou’s movements and moves a hand down, too, pressing right between Bakugou’s legs. “That a problem for you?”

Fucking minx.

“Should be,” Bakugou says. Kirishima frowns and halts his movements entirely, arms shifting to rest on Bakugou’s shoulders instead. “No, don’t—keep going. It should be a problem. But it’s not, not with you. Fuck.”

“You… You want to… Me that bad?”

“Want to what?” Bakugou challenges, a smirk playing at his lips. Kirishima already rarely swears as an adult—the idea of him doing it as a teen gets him going, somehow.

Kirishima’s face flushes even redder. “Want to—want to, ah,” he cuts himself off with a breathy sound, spurred on by Bakugou sliding his right hand under Kirishima’s briefs.

“Huh? Keep going, Eijirou,” Bakugou teases, running his calloused thumb over Kirishima’s tip, smearing the pre-come seeping from the slit. It’s so overwhelmingly different from what he’s used to, and Bakugou has to remind himself this kid is still going through goddamn puberty. “Tell me what you think I wanna fucking do, go on.”

“To, ah, you want to fuck me?” He says it like it’s a question, biting his lower lip and looking away.

Bakugou starts jerking him off in earnest, doing it the way he’s had many years to learn, just like Kirishima enjoys it ten years in the future. “Fuck yeah, I do,” he says, moving to bite the soft skin of his shoulder. “Wanna fuck your tiny little body so fucking bad, Ei. You know where I wanna fuck you?”

Kirishima’s eyes roll back and his head hits the wall with a thud. He doesn’t seem bothered by the pain, though. “Ah, Katsuki, oh my God—”

“Say it, Ei, come on,” Bakugou breathes. He’s so fucking hard, just from hearing this kid choke and whine and cry out, from debauching him until his eyes are teary and his face is completely red, and it feels like Bakugou’s going to burst.

“You wanna fuck me, ah, in my ass,” Kirishima breathes, legs struggling to stay firmly wrapped around Bakugou.

“Fuck,” Bakugou groans. He starts rutting against Kirishima, reminiscent of the way they used to do together back when Bakugou would bring him over to his dorm room, and the thought that the boy in front of him hasn’t even gotten to experience it yet makes his head spin. “And you want me to do it? Put my cock in your virgin ass?”

“Yeah,” Kirishima moans, unashamed. He doesn’t need to be told to keep going by now. “I want you to fuck my ass, fuck, I want your dick so bad, Ground—no, Katsuki—”

“Feels fucking good, huh? To finally do all this shit with a man?” Bakugou says, and Kirishima’s eyes widen for a moment, and he worries he’s crossed a line. But it turns out fine—Kirishima goes limp and his orgasm washes over him, staining his button-up with come as Bakugou milks him dry, until he’s completely exhausted and slumps against Bakugou’s shoulder.

Kirishima doesn’t last long and ends up falling asleep. And Bakugou doesn’t do this mushy shit, that’s Kirishima’s thing—but looking at the kid in his arms, still the man he’s engaged to but with soft hair and baby fat on his cheeks, he can’t help tucking him into the king-sized bed that, in retrospect, they could’ve used.

*

Bakugou is a man of his word.

“You ever have something in here before?” He asks, rough fingers digging into Kirishima’s cheeks, kneading them apart so he can get a better view of his hole. “Try playing with your fingers or some shit like that?”

Kirishima’s on all fours, facing away from him, but Bakugou knows he’s blushing like mad. He knows it, because he’s been doing all of it intentionally for the past hours—the teasing, the comments about his dick size when Bakugou makes Kirishima wrap his hands around both of their hard-ons. Flustering this kid is just really, really fucking fun.

“Never,” Kirishima whispers. This, too, is intentional. Bakugou knows very well his experimental phase hadn’t gone past masturbating to buff men in magazines before future pro hero Ground Zero came along.

“Thought so,” Bakugou says. “You’ve seen my dick. And you look real fucking tight. Think you can actually do it, huh?”
Kirishima gasps when Bakugou presses his thumb over his puckered hole, rubbing light circles, his other hand playing with Kirishima’s balls.

“Please, ah—you have to stop, else I’m gonna—”

Bakugou grabs his shaft and barks out a laugh. “Oh no, you fucking won’t,” he says. “Not until I’m done with you. And if you do, you’ll just have to come again and again til I do too. Get it, punk?”

Kirishima doesn’t answer. Bakugou smacks his ass, hard enough to catch him off guard. “Yes, yes, I get it,” he cries.

“So, Ei,” Bakugou says conversationally, as if he’s not zipping open the intimacy kit Kirishima had gingerly brought from the bathroom. “You know what this is for, right? Use it.”

He moves around the bed and kneels on the pillows, his cock right in front of Kirishima’s burning face. He hands Kirishima an uncapped bottle of lube.

“Huh? I—”

“You don’t want me to fucking go in dry, do you?” Bakugou interrupts. Kirishima shakes his head, a terrified look in his eyes. “So come on. Get it on my dick. Get it wet so I can fuck your little ass. Understand?”

Kirishima shifts his weight to his elbows and squeezes the lube out, enough to cover his whole palm. He rubs his hands together, smearing all of it, and shuffles closer. He’s hesitant when touching Bakugou’s cock; Kirishima’s hands are small, he needs both of them to properly hold Bakugou’s shaft, and it drives him crazy.

“That’s it,” Bakugou talks him through it, groaning as Kirishima spreads lube over the entire length. “Touch all of it. I know you want to get your hands on me, don’t you?”

An excited nod. Kirishima moves as if to play with Bakugou’s balls, but he grabs his wrist before he can do anything. “What do you think you’re doing?”

Kirishima stammers. “I—I was going to…” His mouth hangs open, wordless, and Bakugou briefly thinks about how his throat would feel tightening around his dick. “To touch you there.”

“For a petty delinquent, you’re sure ashamed of fucking words, kid,” Bakugou says, glaring down at him. “Am I gonna have to ask you to use them every goddamn time?”

“No! I—I was going to, to touch your balls,” Kirishima whispers. He doesn’t meet Bakugou’s eyes, but he deems Kirishima’s efforts good enough and lets go of his wrist.

“Go on, then,” Bakugou cocks his head at him.

Kirishima’s eyes almost sparkle. Bakugou wonders if he’s been a sexual deviant waiting for this moment all along. He uses his left hand to keep on jerking Bakugou off like he’d been doing before, but uses his right to experimentally roll Bakugou’s balls in his palm, playing with his sac.

It earns him a choked noise from Bakugou, and that’s the highest possible reward—he hopes Kirishima’s fucking thankful. But however exhilarating it feels, he’s also really, really eager to fuck Kirishima, and if this drags on any longer, he may sweat enough to explode the whole hotel.

“Get on with it,” he orders. Kirishima, always scrambling to obey, lets go and allows Bakugou to move back to his previous position, kneeling behind Kirishima’s scrawny body. “Nervous?”

“It’s my first time, so, y’know,” Kirishima trails off. Bakugou hums. “But—but I want you to do it, I really do, I think you’re really hot and you’re probably a great hero—”

“Yeah, I fucking know, kid,” Bakugou cuts him off. “Less talking, more getting yourself nice and ready for me.”

Kirishima inhales and moves his hands back, putting them over his own ass and slowly, slowly spreading himself open, putting his puckered hole on full display, all for Bakugou.

“Look at you,” Bakugou says, amusement tinging his voice. “So tiny. Don’t even know if I’m gonna fit inside.”

Kirishima whines, like he’s a goddamn bitch in heat. Bakugou keeps talking to spite him. “Bet you’re gonna be so good, gonna be like a cocksleeve clenching around me. You want to be my little cocksleeve, Ei?”

He bows his head and bites a pillow. Bakugou waits until Kirishima mumbles a shy “I wanna.”

Bakugou doesn’t reply. He takes his lubed up cock in his hand, pumps himself once, twice, and presses his cockhead against Kirishima. He pushes in with some effort, a low moan snatched out of him by the warmth swallowing his dick.

Kirishima is so, so fucking small. It feels like his asshole is sucking Bakugou in, his puckered hole twitching and begging for more as Kirishima throws his head back and cries Bakugou’s name. Each inch is agonisingly slow, and he drinks in Kirishima’s every reaction, his sharp teeth tearing the pillowcase, his stubby nails holding onto the white sheets, his head turning so he can look Bakugou in the eyes as he ravages him.

He pushes in, groaning until his balls hit Kirishima’s taint. Bakugou swears under his breath. “That good?”

Kirishima’s answer is barely coherent. “Yes, yes, fuck yes—ah, so full, oh my God, yes,” his eyelids flutter shut and he drools on the pillow, and it should’ve thrown Bakugou off, but it makes his cock twitch inside Kirishima.

“So what now, huh?” Bakugou asks. Kirishima hums quizzically. “I don’t really know what to do. I think you’re gonna have to walk me through it.”

Kirishima lets out a high-pitched whine before he starts babbling. “Katsuki, Katsuki, please, please just do it,” he says, stumbling over his own words, too overwhelmed to form proper sentences. “Wanna, wanna feel your cock. Your big cock, please, Katsuki.”

Bakugou indulges him and starts moving, shallow thrusts barely getting the edge off. “My big cock, huh? You like it that much?”

“Love it,” Kirishima answers, voice cracking, and Bakugou can’t tell if it’s because of puberty or how needy he is. His little cock is leaking all over his soft skin. “Fuck my ass, please, I—”

He doesn’t get to finish that sentence; Bakugou tugs at his black hair and starts properly fucking him, pushing Kirishima’s head down and thrusting relentlessly until the boy comes the first time, dirtying his flat stomach.

“Remember what I said before?” Bakugou says, not slowing down for a single second. “You’ll keep on coming til I’m done with you.” He keeps on moving, revelling in the warmth of Kirishima’s ass and the way he clenches around his cock, tightening so hard when being fucked for the first time.

Kirishima tries to turn around to look at him and it’s beautiful. His chubby cheeks are pink and swollen, and his eyes are glossy with tears, sweat dripping from his forehead. Bakugou feels almost dizzy. It’s Kirishima, who he’s loved and slept with for years, but it’s also someone else, a teenager with a boyish charm Bakugou can’t resist. With a dirty, slutty mouth that screams out “Katsuki!” as he orgasms once more, letting Bakugou pound into his sated, fucked out body.

Bakugou’s hands run wild, trying to hold onto every inch of Kirishima so he can map out his still unscarred skin, the soft chub Bakugou’s never seen Kirishima with. He traces the knobs of his back, where he knows his present Kirishima has gotten a scar from a raid. He lets his rough fingers linger right above Kirishima’s navel, where there will be a gunshot wound Bakugou helped him recover from.

“God, fuck, you’re going to be the greatest hero,” Bakugou says, and he lets go. He pulls out, leaving Kirishima’s hole twitching, attempting to tighten around something, and pumps himself until he dirties Kirishima’s back with his come.

They both slump carelessly on the bed, lying in the sticky mess of come and sweat. Normally, Bakugou would be bothered, but his brain feels hazy. Made of cotton.

“Shit,” he gasps. “Fuck.”

Kirishima hums. “M’tired, man.” He crawls closer to Bakugou, close enough for Bakugou to sling his arm around his thin waist. “Wanna sleep.”

“You’re disgusting right now, Ei,” he groans, hoarse voice muffled by Kirishima’s messy hair.

“S’re you,” Kirishima says, right before he falls asleep for good, and Bakugou doesn’t even get a chance to argue.

*

Bakugou wakes up with a smile on his face, which is increasingly common since his engagement, but still a weird oddity.

He panics for a second when he doesn’t recognise his surroundings, then everything comes back to him—Warp, Chiba, his extreme disregard for Yaoyorozu’s Physics theories, Kirishima.
The boy is still fast asleep. Bakugou allows himself to stare for a while, drinking in the soft features before a strange, familiar tingling covers his fingertips.

It’s the same itch he’d felt when Warp got a hold of him.

Bakugou shakes Kirishima awake, lightly slapping his face. “Eijirou, Eijirou, Eijirou!”

Kirishima blinks. “Huh?” Is all his sleep-addled mind can come up with.

“Eijirou, look at me,” Bakugou says, feeling Warp’s Quirk spread up to his elbows and bloom in his feet, slowly licking up his legs. When Kirishima finally looks focused enough, he sighs. “The villain that got me here—he’s taking me back. Okay? And I… I have nothing to say, I think. But,” he breathes in.

“I meant what I said, back when we. Fucked. You’re going to be the greatest hero. I’m so fucking proud of you, Ei,” he continues. “This might’ve been about, I don’t know, sex, your gay awakening, whatever. I can’t lie and say it fucking wasn’t. But I love you now, and I will love you in the future too. So you just—you’ve got to be fucking strong, alright? Be the dope ass hero I know you’re gonna be.”

He can’t hear what the younger, black-haired Kirishima says. It’s fine. The 24 year old, red from top to bottom Kirishima is hovering, tending to Bakugou’s minor injuries.

*

“Get your head out of your ass, Ponytail,” he hears someone say, rather, yell. “Not all of us can be spoiled rich fucks!”

Kirishima walks through the terrifyingly huge door into his new classroom. And there, legs propped up on a desk with complete disregard for the guy with glasses scolding him, is Ground Zero.

(He flushes from head to toe.)