Chapter Text
The first time it happens Bucky’s fast asleep. He lurches upright so suddenly it actually takes him a second to reorient, and when he does he’s pleased to see that he’s got a knife in his metal hand and his teeth bared, ready to sink alpha fangs into an enemy. So ha, take that, Sam Fucking Wilson, he hasn’t aged so much that he’s lost his instincts.
Except a knife and some fangs isn’t going to be much help against this particular threat, because he hasn’t been woken by someone breaking into the apartment, or aliens whizzing down the street outside his window, or anything that could even tangentially be fixed with stabbing. More’s the pity. He appears to have instead been woken up by, of all things, food poisoning. There’s a hot cramping sensation in his lower belly and he feels sweaty and gross.
Oh, ew. Not cool, body.
Clint’s crouched near the doorway, poised between reaching for the light and reaching for the Avengers alarm, waiting for Bucky to give some indication about the non-existent threat that’s sent him careening out of bed at ass-o’clock.
Fight? Clint signs in the dark, trusting Bucky’s eyes to catch the word even though Bucky’s pretty sure it’s too dark for Clint to see any reply Bucky makes.
Bucky feels himself flushing. He’s woken Clint up for nothing. Hell, maybe he is getting old. Maybe his super-serum is slowing down. He bets Steve doesn’t get hassled by his digestive system.
“S’all good,” he says, out loud, immediately bringing Clint out of his defensive pose. “Go back to sleep.”
Inconveniently, Clint flicks on the bedside lamp instead. Bucky quickly turns aside to ferret the knife back into its spot beneath the mattress, letting his hair hide his flushed cheeks. He knows he doesn’t need to protect his night-vision; they’re not at war, and he and Clint aren’t even on call for any Avengers business right now. But he pretends that’s what he’s doing as he keeps his face turned away, skirting Clint wide enough that he hopes Clint can’t smell his embarrassment before padding into the kitchen.
Clint follows behind him. Damn.
Clint hops up onto the kitchen counter and kicks his bare feet. He smells good, but then that’s nothing new. He always smells good. Cedar and warm, sleepy alpha. His knees are far enough apart for Bucky to step between them, but Bucky opens the fridge door and pretends he doesn’t notice the silent invitation.
“Nightmare?” Clint asks, propping himself up with one hand behind him and one hand scratching idly at his belly. A bandaid beneath his ribs is starting to curl up at the edges.
“No,” Bucky mutters, and stares at the stuff inside the fridge instead of collapsing into Clint’s lap to kiss the bandaid flat and to get his head rubbed or something equally mortifying. It’s just a belly ache. He used to get these all the time as a kid.
At first glance, there’s a dozen potential culprits in the fridge. Takeout leftovers, half-eaten meals, and pots of miscellaneous “food” from Clint’s various attempts at “following a recipe.”
Bucky pokes at a pizza box, trying to remember which foods he ate yesterday that Clint didn’t, since clearly Clint’s unaffected. Everything smells a bit gross, actually. Maybe they should just throw it all out. There appears to be a human tooth in the crisper.
“Oh, I was looking for that,” Clint says, watching from over his shoulder.
It would make more sense to deal with the hypothetical bad food in the morning, but Bucky’s skin is itching and he’s hyped up like they’re gearing for a fight, which feels like it’s a weird symptom to get from old food, but then again what would he know?
He goes to get a garbage bag. By the time he’s scrounged something out from under the sink Clint’s hopped off the counter and is pouring himself a glass of milk. Bucky pauses to watch him, lit up in just the light from the open fridge door like some kind of cold storage angel. He briefly considers telling Clint that the milk might be bad, but they’d bought it only yesterday, and he’s distracted by the line of Clint’s throat as he tips his head and swallows.
Clint raises an eyebrow at him, and Bucky realises he’s just standing there, staring. The fridge makes a polite little warning beep. Shh, fridge. Don’t distract Clint from doing the thing where he stands around shirtless and barefoot and good enough to eat. Which is lucky, because if the food inside the fridge isn’t bad yet, it will be soon. Honestly, Bucky would be a-okay surviving on an all-Clint diet.
Clint offers him the glass he just drank from. It’s not exactly like an alpha bringing a kill back from a hunt, but something fuzzes nicely at the back of Bucky’s head, and, surprisingly, his stomach stops cramping. Oh. Maybe it isn’t food poisoning after all. Maybe he’s just hungry. Or thirsty. Looking at Clint in the half-light-half-shadow he sure feels hungry and/or thirsty. He takes the cool glass and sips, and Clint makes a low, pleased sound, so he does it again. When the glass is empty Clint takes it from him and puts it in the sink, kicks the fridge door closed without looking at it, and then walks him backward towards the bedroom with hands on Bucky’s hips. Bucky lets himself get herded. He doesn’t usually like getting pushed places, but when Clint does it it’s… nice. Strategically correct. Like going exactly where he’d planned to go anyway.
“Sorry,” he murmurs, as Clint pulls the blankets down and waves him in. “Thought I was getting sick.”
“Mmh, you did smell a little strange.”
Bucky shrugs. Whatever the weird belly cramp had been, it’s stopped now. Maybe his useless knockoff serum just needed a moment to work. He feels lazy and soft in the aftermath, and scents at Clint happily when he joins him under the covers. It’s not until Clint presses up against him properly that he even realises he’s hard. How strange.
He doesn’t know if he’s hard because he can smell Clint’s arousal, or if it’s the other way round. He huffs a laugh. Years together, and he’s still so horny for him. Even when he doesn’t realise that he is.
Clint rolls them a bit so he’s lying on top of Bucky, which is presumably like lying on top of a concrete slab. But Clint makes a happy snuffly sound, going completely boneless and smelling about as good as he’s ever smelled, so Bucky figures he’s probably exactly where he wants to be. Which is lucky, because Bucky feels remarkably comfortable right now, too. Pressed into the mattress with his alpha’s scent in his nose and his alpha’s warm body above him.
Clint’s thigh slips in between his own, and Bucky arches up into him.
“You wanna?” Clint asks, rocking his hips. Bucky’s already patting around the bedside table for the lube.
The second time it happens he’s on a run. He’s jogging past the fountain that the local kids keep putting dye in, noting a construction zone down the street which might impact the sight lines of his normal patrol (does the city council not consider these things when approving shit?). And then there’s a hot, mean pulse in his lower belly. Like someone’s hand is curling into a fist in there. Fuck, this isn’t food poisoning. What the hell is it?
He swerves off his normal route and into an alcove he’d identified months ago as a potential cover point from enemy fire. Except no one’s shooting at him right now. Damn. Maybe if he yells enough someone will pull a gun out, just to give him a threat he knows how to handle. He puts a hand on the brickwork and bends forward and presses his metal palm over his stomach, pushing, like he can squash whatever it is that’s mucking up his insides.
As he stands there, trying to figure out his next move, he inexplicably thinks of Clint. He remembers that Clint is still at home. He can’t quite figure out why this thought is so distressing, but as soon as he’s pictured Clint—probably napping in the warm spot on Bucky’s side of the bed—the thing inside him twists and he gasps, springing an instant cold sweat. Clint’s all alone. Or else it’s Bucky who’s all alone, even though there are pedestrians just around the corner. One of them is all alone, in any case, and it’s not right.
He pushes off the wall, swerves onto the sidewalk, and reaches top speed before he’s even hit the end of the street. He sprints all the way home, and finds Clint exactly where he left him, facedown in Bucky’s pillow even though Bucky’s sure he can’t breathe like that. Clint’s always adamant that suffocating on Bucky’s scent is a good way to go, but Bucky doesn’t want him suffocating right now. He hurtles onto the bed and catches Clint’s instinctive back-kick—once, twice—until Clint wakes up enough to smell that it’s him.
“Buck? Whaddarya—”
Bucky flops down on top of him, and Clint makes an oof sound but doesn’t smell at all annoyed about two hundred pounds of sweaty, post-run alpha plastered against him. In fact, he reaches a hand behind his shoulder to pat blindly at Bucky’s face, then fist his hair a bit, shaking. Bucky groans and scents up the back of Clint’s neck, chasing the relaxed sleepy smell that’s quickly banishing the terror that had seized him on his run. Had it really been terror? Surely not. Clint is safe, and warm, and curled up in the bed that smells of both of them.
Clint hooks an ankle up and over Bucky’s knee and rolls. Bucky doesn’t even get a hint of his old training resurfacing. There’s no part of him that feels the need to fight the hold. In fact, he assists, grabbing Clint around the waist to properly situate him on top. Which is, tactically, completely nonsensical. Clint squirms (hello!) until they’re face to face, with his knees on either side of Bucky’s thighs.
“Aw,” Clint coos, sitting up with a hand planted on Bucky’s chest. “Did you get horny on your run and decide to get some cardio a different way?” He grinds his hips meaningfully and Bucky realises he’s hard.
Oh. Well, okay. Is that what had happened? How embarrassing. But not embarrassing enough for him not to admit that, actually, yeah, getting fucked right now sounds amazing.
He tilts his head up and tugs at Clint’s waist again, angling for a kiss. Clint laughs and holds off, leaning instead for the bedside table. Bucky gets a hot rush of anxiety. Does Clint not want to kiss him? Is Bucky no longer appealing to his alpha? Shit, he should have showered first. He should have—
But no, Clint is just reaching for a mint strip and a cloth, which he hurriedly rubs against his gums. Because Bucky hates morning breath. His senses are so overwhelming sometimes and Clint keeps little packets of scent neutralisers and mints and the like so Bucky’s never swamped with sensory input.
Usually Clint’s little Bucky-specific habits make him feel fond and a little embarrassed. But right now he just feels confused. He doesn’t want Clint to do something that delays kissing. He hadn’t even noticed the morning breath. It’s not that his senses are dulled: if anything, they feel hyperactive. His skin is alight at all the points of contact. Clint’s steady hand on his chest. His legs folded outside Bucky’s thighs. His weight pressing Bucky into the mattress. What is going on? He’s sweaty and sticky and—
And then Clint finishes his quick hygiene routine and kisses him, and all thoughts of discomfort flee. Clint’s lips are so warm, and Bucky opens immediately for him, groaning as Clint’s tongue slips into his mouth, minty and perfect, licking up behind his teeth so it feels like he’s tugging at the back of Bucky’s incisors, urging Bucky closer. Bucky wishes he could get closer, but they’re already plastered together from nose to navel. He wants to put his hands in Clint’s hair, and around his neck, and behind his shoulders. Anywhere that will hold their bodies flush. But he finds that he can’t move his arms at all, only cling weakly to Clint’s waist and whine.
“What is it, baby? What’s wrong?” Clint kisses over Bucky’s cheek towards the sensitive lobe of his ear, sucking it into his mouth and making Bucky’s whine stutter.
“Nothing,” Bucky manages, doing a horrendous job of the whole calm cool collected assassin thing. Something is definitely wrong, but the longer Clint touches him the more he realises that the thing that’s wrong might be himself.
“What do you want?”
Well, that’s easy enough to answer.
“Fuck me?” He hates that it comes out as a question. He hates that he sounds needy. Clint has never turned down an opportunity to fuck him. But he can’t shake the feeling that there’s something he needs, and Clint is withholding it. Like Bucky’s sighting down a scope but there’s no target in the crosshairs. He’s wrong-footed and confused.
Except then Clint grins against his wet earlobe, and his scent goes pleased and predatory, and Bucky feels his whole body relax into the mattress like just the promise of a cock is enough to turn him into a big pliant Bucky-sized ball of goo.
“Maybe I really should start coming on your horrible morning runs,” Clint says, somehow making it sound flirty. He starts peeling Bucky out of his clothes. Which is about as pleasing a trajectory as Bucky could ever want. There’s a target in the crosshairs after all. Clint kisses one of his nipples (oh, fuck), licks over to the seam where flesh meets metal (oh, fuck), and then trails his mouth up Bucky’s neck to reach his ear and add, voice dark with promise, “If it gets you this worked up.”
(oh, fuck)
Bucky valiantly corrals a few stray brain cells together to formulate a response. “Steve says that exercise in the morning is—”
“Steve,” Clint scoffs, and Bucky spasms beneath him at the sound of another alpha’s name in his mouth, even though he was the one to say it first. What in the—
And then Clint’s hand closes around his cock and anything that isn’t getting fucked right this instant becomes so categorically unimportant that he pretty much loses the power of speech. Which, as it turns out, is a good thing. Because otherwise he’s pretty sure he’d be singing poetry or yodelling or something as Clint repositions. Clint grips one of his ankles to hoist it up and out, spreading Bucky so casually as he makes room for himself between Bucky’s legs.
It’s nothing they haven’t done a hundred times before, but for some reason this time feels impossibly hotter. Clint’s fingers, and then his cock, and then the smooth wet slide of him that goes on and on and on, filling Bucky so good that he forgets about his own pleasure entirely, lost in the unbelievable stretch, and the way Clint never leaves him empty for long, sliding right up into him over and over. When Clint’s knot starts to catch, Bucky hooks his raised ankle behind Clint’s back, trying to hold him in. He’s unreasonably terrified that Clint will knot on the wrong side of Bucky’s body, even though that hasn’t happened since the early days when they were still learning each other’s rhythms.
Clint, maybe smelling Bucky’s fear, presses close, grinding his hips against Bucky’s ass so the head of his cock is as deep as it can get. Without the physical thrusting his knot takes longer to fully lock, expanding only in incremental starbursts of pleasure, each tiny addition so good Bucky thinks it can’t possible get any better, except then it does, bigger with every heartbeat until he’s impossibly full and still, somehow, getting fuller. Alphas aren’t as easy to knot as omegas, but they’re well-practiced by now, and Bucky knows it’ll fit. Doesn’t mean it isn’t a hell of a stretch.
“Fuck,” he cries, apparently relearning the powers of speech just to curse.
“So good for me,” Clint coos. “Oh sweetheart, oh love.” His knot catches fully, and every muscle in Bucky’s body goes limp simultaneously, like some ancestral slice of genetic code knows exactly what it means to be tied. He’s panting like he sprinted home in full armour, even though it’s Clint who did the bulk of the work fucking him.
“Alpha,” he whispers, as he feels Clint fill him up. It’s so perfect. Maybe it’ll catch and he’ll get all pupped up. He’ll be big and round for his—
He blinks. Woah, okay. Where did that come from? Cool it, libido. There’s a fair bit of anatomy that might have something to say about the possibility of pupping!
Later, as Clint wipes him down with a warm, damp, cloth, Bucky realises that he must have come, too. He doesn’t remember it happening. He’d been so focused on the feeling of Clint. Of Clint filling him and knotting him and spilling inside him.
He thinks he should worry about it some more (and maybe do some introspection about the acquisition of an impregnation kink, damn), but then Clint’s crawling naked into the bed with him and even though the day’s just starting there’s nothing wrong with having a morning nap. It’s definitely healthy to have naps while being cuddled by the world’s hottest alpha. There’s probably like, science about it and everything.
Clint rumbles happily against the back of his neck and any niggling worries instantly vanish as he slides down into sleep.
It happens a third time, and he finally goes to the team doctor. He knows he’s scarlet through the entire meeting, but Dr. Cho is characteristically professional. She jots notes on a tablet as he describes making breakfast that morning before being overcome with a cramp so strong he could barely uncurl to turn the stove off. It hadn’t abated until he’d staggered into the bedroom to find Clint freshly showered, completely naked, hair dripping. (Objectively one of the best ways to find Clint.)
“Did the pain reduce when you walked into the room, or only when you touched Mr. Barton?”
The question is specific enough that Bucky thinks she already knows what’s going on. Thank god. “Both,” he says. “His scent, first, and then his, his—” Hydra trained embarrassment out of him, for the most part, but there’s still a voice that sounds suspiciously Sarah-Rogers-esque that thinks he ought to mind his tongue in front of a lady. Cho waits patiently as he attempts to fumble through the explanation of getting knotted without using the word penis. Or alluding to his knowledge of the existence of penises at all.
He thinks he’s done an alright job of it, too, right up until Cho says, “So, what happened after you were anally penetrated?”
Yeah, well, don’t say he didn’t try.
Dejectedly, he describes the desperation that just hadn’t seemed to let up, and how good it had felt to be touched. How it had felt so good he hadn’t even cared about coming himself.
He tacks a “ma’am” onto the end of his impromptu sex confession (sexfession?) and hopes Ma Rogers is appeased. The last thing he needs is a vengeful spirit coming to chide him on his manners.
“I would like to know more about your relationship with Mr. Barton,” Cho says, because of course she does. Sorry, vengeful spirit, please block your ears.
He closes his eyes and lets her steer him through a thorough description of their sexual history. Yes, they both used to knot each other, but lately it’s just been Clint. How long? Oh, years. They both prefer it that way. Yes, he achieves orgasm every time. No, he doesn’t need manual stimulation, just the knot.
“Thank you for your responses,” she says, putting the tablet down.
“Is it the withdrawal again?” Bucky asks, dreading the response. Getting weaned off Hydra’s cocktail of drugs had been supremely awful. For everyone. He’d gone months barely tolerating touch, then barely tolerating its absence, glued to literally anyone who happened to get within grabbing distance. Clint, mostly, but also Steve, Sam, Nat, and once—terrifying for everyone involved—Hulk. He’d cartwheeled through mood swings and hormonal imbalances like his bloodwork was attempting to recreate a Pollock. There had been a whole fortnight where he hadn’t been able to see any colour below 500nm, which had turned Clint’s eyes a muddy grey. Though he hadn’t admitted it at the time, this had actually been more distressing than the touch thing, and the first time he’d woken up to see Clint blinking bleary blue eyes at him he’d almost cried.
But it’s been years since Cho and her team balanced his hormones and perfected the exact chemicals required to keep him fit and healthy and pain-free.
Cho looks over his left shoulder and Bucky looks over hers, which is as close to eye-contact as he can get with most people. “They’re micro-heats,” she says. He can tell that she’s struggling to remain inflectionless, which makes his own heart rate pick up as she breaks the news. “You’re experiencing a late-onset omegatisation.”
The fourth time is, frankly, dreadful. Despite his best efforts he can tell that Clint knows something’s up. He tries to lie his way through any sticky questions, but he’s an assassin, not an undercover agent. The only interrogation training he’s ever received is how to avoid interrogation entirely, which is hardly useful when Clinton Francis Barton has him cornered and is doing his best impression of an orphaned puppy sitting in the rain.
Bucky tries hiding out in Steve’s spare room, but makes it exactly one “Are you sure you’re alright, Buck?” before remembering who invented the orphaned puppy eyes. He sulks back to his own floor. Fortunately, he must look pathetic enough about it that Clint lays off the questioning for a bit and invites him to an impromptu let’s-beat-up-some-mobsters session followed by a let’s-snuggle-in-bed session instead. Immensely appreciated.
And then the cramping starts.
Bucky sneaks out of their bed before the sun’s even up. He feels like the other woman in an illicit affair. Like he should be leaving via window. They’re on the 28th floor but he’d probably make it. Falling’s a bit of a speciality of his. Look out below! Flying cyborg!
He barricades himself into the med room he provisioned for exactly this purpose. He activates the containment protocols—they were designed for the Hulk, so they’ll withstand one puny hurting alpha—and then hunkers down in the corner with his head in his hands and resolves to dissociate his way through the next hour.
Except it doesn’t end after an hour. It keeps going. If anything it gets worse.
He grinds the heel of his hand into his stomach and decides that this is all Clint’s fault. He’s going to demand, just, the longest blowjob after this. His abdomen tightens miserably and he amends his demands. Five blowjobs. And a back rub.
He can’t even feel that smug about it, because he knows Clint will do it anyway without Bucky needing to explain why. Even at the height of the drug withdrawals, when Bucky hadn’t known what his body needed, only that it needed the mystery thing immediately, Clint had been stoically good-humoured.
Thinking about Clint isn’t helping his current situation. He keeps getting overwhelmed with the urge to go and find his alpha. Knowing that his hormones are emotionally manipulating him only makes it marginally easier to ignore.
“Fine,” he grumbles at his own stomach. “You wanna talk? Talk.” He pulls out the rolling cart with the ultrasound machine and preps his belly exactly the way Cho had done it. It’s a bit harder doing it to himself, and at one point he almost severs a cable when it gets stuck in between two plates in his left arm, but after a little (a lot) of swearing and very careful maneuvering he eventually has a clear image on the screen. Well. “Clear” might be an overstatement. There are some blobs on the screen. The tower’s AI tries to be helpful by identifying them for him, but since his medical records have him listed as an alpha it has a hard time with what is, undoubtedly, the immature organs of an omega’s budding reproductive system.
His anatomical knowledge has mostly developed as a result of being in the very-near vicinity of recently-disembowelled corpses. He knows what each organ looks like (squishy), feels like (squishy-ish), and smells like (not great). He knows which ones can be pinched, perforated, or removed to achieve the desired outcome (death) in the desired timeframe (now). It’s always astounded him how much stuff can fit inside someone. The ultrasound images are far less messy, but even he can tell that there’s no extra room in there. No wonder everything aches. Where the hell do omegas fit all this?
Notably, the blobs are bigger than they were last week in Cho’s office.
His abdomen tightens, and he gets the dubious pleasure of watching the cramp in real time on the screen.
“You can’t possibly need a knot,” he tells the blobs through gritted teeth. “What conceivable reason could you have for needing a knot?” Conceivable being the ten dollar word, actually.
The blobs flex minutely. The tiny movement is at complete odds with the magnitude of the pain. Thanks to the reading material Cho sent him, Bucky knows that an alpha knotting him will signal his new reproductive system to continue development, with the promise of imminent alpha seed incoming. But the whole process makes so little sense it just doesn’t seem possible.
He calls Cho.
“They’re getting bigger,” he says, not bothering with a hello.
“And since our last meeting you and Mr. Barton haven’t…”
“No.” Lamentably.
“Then I’m afraid the process is irreversible.”
Yeah, he’d figured. “Acknowledged.”
“Everything okay, Buck?” Steve asks. Oh.
“Steve’s with you?”
“Captain Rogers is assisting with the clinical trial of a new suppressant.”
“But I’ll be done soon. This sounds serious. I’ll come by in ten?”
“That’s not necessary.”
“Whatever it is, maybe I can help?”
So god damn earnest. What an annoying time to exercise his mookiness. Bucky utilises the one tactic which always, without fail, gets Steve to avoid him for a few hours. “Well you see,” he says. “Clint’s knot is just so big and he comes so much that I can’t swallow it all at once or else I—”
“Sergeant Barnes,” Cho interrupts, professional calm bleeding into exasperation. “Captain Rogers’ blood pressure just plummeted. You’ve introduced an unpredicted variable into the study design.”
“Acknowledged,” Bucky says cheerfully, and hangs up to the sound of Steve spluttering.
His stomach is still cramping terribly, but there’s literally no reason at all to just let it carry on in merry torment.
“Alright,” he tells it. “You win. My life is ruined. Let’s go get a knot.”
He cleans up his isolation room and goes back to his floor. Clint’s in the kitchen in a Kiss The Cook apron. There are half a dozen pots simmering away, and a seventh pot sitting in culinary time-out in the oven, which means he’s been doing the Clint version of stressing—probably about Bucky—and tried a new recipe without adult supervision. There’s a streak of something glowing faintly purple on his chin, which even Bucky knows isn’t normally a colour associated with edibility.
Despite everything, the smell of him is instantly soothing. He’s wearing a singed left-handed oven mitt on his right hand (?) and is holding a rolling pin, which he appears to be using as a spoon, in the other. Tragically, he isn’t naked beneath the apron.
“Right,” Bucky says, remaining focused even in the face of Domestic Clint. “I have some news for us to panic about. But first you have to knot me.” He starts turning burners off. “And also you promised me five blowjobs and a massage.”
“I did?”
“You weren’t there at the time, but yes.”
He kisses the cook.