Most of the time, honestly, Sam doesn't know what the hell is going on with Steve and Bucky.
At first, he thinks they're friends, that friendship that goes so deep it's the kind of love that hurts. He gets it. Sam and Riley were the same, before Riley went down. Everything Steve's done for Bucky, Sam would have done in a heartbeat if it was Riley on the line. Bucky's a little shit even when he's not being the Winter Soldier, but Sam figures you can't always pick 'em, and he's willing to be civil for Steve's sake.
Plus, Bucky jumped in front of a kid in a spider onesie to stop him kicking Sam off a balcony. That kind of shit gets you a long way, even if they did all wind up going over and Bucky fucking landed on him anyway.
Anyway, Sam thinks he's got them figured out, and it's fine, it's honestly fine, and then Bucky's brainwashing gets cleared, and they move into a house together like they're all friends, or something, and they can actually function in a house built for normal people.
Three days in, Sam has no idea what the fuck Bucky and Steve are. Everywhere he looks, Bucky is basically in Steve's lap, or curled up against him as close as he can get. One time, Sam finds him wearing Steve's sweater, huddled into it like maybe it still smells of Steve.
Huh, he thinks, and adjusts his expectations. It's no big deal. So Steve and Bucky are dating, maybe, that's not- kind of not what Sam expected, honestly, but it's no big deal. It's fine. It's one hundred percent fine.
It's just- well, it's just. Bucky is an asshole, and Sam kind of hates him, but he's got eyes. Under the stubble and the truly terrible hair, Bucky has exceptionally blue eyes and the kind of mouth Sam's not ashamed to call pretty, and he just. Sam kind of enjoyed the whole I hate you thing, if he's being honest. It felt like maybe it was going somewhere. If it's not, that's fine, Sam can handle that, he just has to tolerate them being so fucking cuddly everywhere.
The weirdest thing, he thinks to himself, is it never goes any further than that. He never sees them kiss. He's pretty sure Bucky's slept in his own bed every night since they moved in. Maybe they're taking it slow. Maybe they're just not into PDA. Maybe Sam should just stop thinking about it, Jesus Christ, and let it go.
Then Steve takes up knitting, because honestly, he is a ninety-year-old woman in the body of an unfairly muscled American god. It's the worst. Everything Steve turns out is crooked, stitches dropped all over the place, and he uses the worst fucking colors, sweaters in nothing but itchy navy wool, hats that are way too fluffy for Sam ever to even consider putting on his head. Lumpy socks. It's dire.
Who the fuck taught Steve to knit, he texts Nat, because if anyone knows she will, and he just gets back an emoji closer to her smirk than he even knew exists.
"So, you, uh, you knit," he says a couple days later, looking at Steve's hands moving with the knitting needles, and Bucky, from under Steve's left arm, snorts with laughter.
"Yeah, my mom taught me," Steve says earnestly. "Way back in the day, it was something I could do in bed all day while I was sick."
"You made me socks," Bucky says, and Steve smiles down at him, the kind of smile that lights up his whole face and makes Sam feel like there should be bluebirds sitting on his shoulders or something.
"Yeah," he agrees softly, the way he always does when Bucky volunteers memories from before, "yeah, Buck, I did."
"They were fuckin' awful," Bucky says bluntly, "the scratchiest things I ever put on in my whole life. But I wore 'em."
He wears the hats Steve makes. He wears the sweaters. He wears the gloves, ugh, they're burnt orange and dark red stripes, fingerless, and Sam is personally offended by how ugly they are, but Bucky just pulls them on, flexes his fingers, smiles very small. Honestly, Sam thinks, feeling very resigned, this is closer to proof that Bucky and Steve are Bucky and Steve than anything else he's seen so far. Only love could tolerate gloves like that.
"Here," Bucky says three days later, "I'll hold your wool," and lets Steve balance the skein on his carbon-fiber palm.
How Bucky got a new prosthetic was a long chain of favors called in. Steve'd called Scott Lang and talked to him for a few minutes in his serious and earnest voice, and Scott had said a lot of things like "heck yeah, man" and "no worries, seriously, that is so cool, call any time, Captain America."
("I'm really not Captain America anymore," Steve'd said, but by this point it's kind of too late. Scott Lang had probably been making puppy eyes at Hope Van Dyne, and Hope had probably rolled her eyes, but then she'd got on the phone with Steve too and Steve was very polite and respectful, and the end result was Bucky looking stoic and expressionless in a Pym Tech lab while Hope'd tinkered with some nanotech genius and a bunch of 3D printing.
"It's lighter than I expected," Bucky'd said afterwards, flexing his fingers and rolling his shoulder thoughtfully. "I- thank you."
“Sure,” Hope had replied, “just make sure, right, if you ever see Tony Stark again, just make real sure to tell him it’s Pym Tech. Rub that right in, okay.”
“Can do,” Bucky'd said, and smirked like he’ll rub it in, alright.)
Sam clears his throat, and looks down at his book, and then can't help it, looks back up. Bucky's leaning back against the arm of the couch, his feet tucked under Steve's thigh, and he's doing something on a tablet with his free hand - YouTube, maybe? He's really into cooking tutorials at the moment. It's sickeningly domestic. Sam suddenly feels desperately left out.
"Man, why exactly are you knitting, these days?" he asks, because he can't not. They've all got new hobbies, living in a safehouse with nothing else to do - Sam's reading all the classics he never got around to - but knitting, come on, Steve might as well be sewing patchwork. Steve glances up, fingers still working.
"Oh," he says easily, "Nat suggested it. She thought it'd be a good way for me to deal with stress and downtime. Honestly, it's really helpful."
You're the fucking worst, Sam texts Nat later. The worst. He learned seventy years ago, you'd think he'd get better at some point.
Get him to knit your robot bird a cozy, Nat suggests, and that's so ridiculous Sam doesn't even deign to reply.
Sam's just chilling watching TV one evening when Bucky comes in and stares at him silently for a minute or two before sitting down on the couch. He's pretty close to Sam.
Okay, he's really close to Sam. Like, Sam would be using the word 'cuddling' if it wasn't so bizarre.
"What," he says, carefully not looking at Bucky, and Bucky huffs a sigh.
"Steve's not here," he says as if it's obvious. "Don't make it weird. Just- shut up."
Sam feels like maybe it's not him making it weird, like, this hundred-year-old cranky ex-assassin who shares a house with Sam now is cuddling him, Steve is away on mission and Sam is being cuddled because Steve's not here, it just. It's weird.
"It's a bit weird," he says, experimentally, and that's apparently enough that Bucky moves to the other end of the couch, his face impassive and emotionless. Sam suddenly feels a little bad.
"Do you, uh," he starts, and sighs at himself, because come on, man, you're trained as a VA counsellor, use your words. "Do you miss him?" Bucky frowns at the TV, does this microscopic little eye-roll that Sam only catches because he's looking hard.
"He's warm as shit," Bucky says like it should be obvious, and hunches down into his sweatshirt, and they watch another ten minutes of Real Housewives of LA before Bucky apparently forgets himself and tucks his feet up onto the couch, stretches sideways and hits Sam's thigh.
"Holy fuck, Barnes, your feet," Sam says in horror, because it's literally like Bucky has two blocks of ice attached to his ankles. Bucky pulls them away.
"Sorry," he says, casual like it's no big deal, "sorry, I-"
"No, man, you're freezing, are you feeling okay? Running a fever? Do you even get sick, with the serum and all?"
"I'm not sick," Bucky shrugs, "this is just... I'm fine. It's fine." Sam thinks for a minute.
"Steve's warm," he catches on, and Bucky nods like it's obvious. "Steve's- that's why you- okay, come here," and Bucky fidgets a little, stares at him flatly, but Sam keeps gesturing for him to shift back over, and after a minute or two of hesitation he does, slides in against Sam's side. Sam snags the throw from the back of the couch, wraps it over Bucky's legs and feet, tucks him in against him, and feels Bucky relax like a full-body thing, feels Bucky's head rest against his shoulder.
"Oh," Bucky sighs after a little while, "okay, you're pretty warm too, this is... yeah, okay. This is good."
"You have trouble regulating your temperature," Sam guesses, and Bucky nods against Sam's shoulder, eyes on the screen. He's quiet for a long time before he says anything.
"The serum they used, it wasn't... Steve got the real stuff, it makes him run about as hot as a furnace most of the time, I'm guessing that's why he came out of the ice with no damage."
"You weren't so lucky?"
"Yeah, or it was never made to last through so many rounds of cryo. I dunno, perhaps it was deliberate. I was designed as a weapon. You don't want your weapon to overheat in the field, right? Running too cold's not a problem if you're only awake during active missions. I was never meant to be left idle."
"Okay," Sam says, carefully neutral, but he tightens his arm around Bucky, and all that's in his head is I will literally set fire to every Hydra agent, holy shit, and Bucky wriggles like he can tell what Sam is thinking.
"Don't tell Steve," he says, "it's, he..."
"Okay," Sam says again. "How're you feeling now?"
"Bit warmer," Bucky says thoughtfully. "You're not a furnace. But you'll do."
"Oh, I'll do," Sam teases, pokes him in the ribs, and that starts a wrestling match which ends with Bucky's hands up under his shirt, fuck, he is straight-out lying about being warmer given his right hand is still the approximate temperature of an ice cube.
"You are warm," Bucky says, and leaves his hands on Sam's bare skin like he can leech some of Sam's body heat.
"You're the worst," Sam informs him, "honestly, literally the worst, we should have left you in the freezer," and Bucky just laughs.
"You could pat my hair," he says hopefully, and Sam frowns but he does it, because they're already cuddling, Bucky's got his hands under Sam's shirt, what's some hair-patting on top of that.
"So you and Steve," he asks, "you're not, like..."
"Ugh," Bucky says, with feeling, "ugh, why would you-"
"You wear his knitting," Sam points out. "Nobody wears his knitting. And you're basically on top of him whenever he's sitting down anywhere. So whatever, I jumped to the logical conclusion."
"His knitting's fucking hideous," Bucky agrees, "but it's warm, you know? I'm not picky."
"Well," Sam says, "okay then," and Bucky promptly falls asleep on him, and if Sam keeps combing his fingers gently through Bucky's hair, whatever, that's up to him. Maybe he falls asleep too. It's quiet, and he's warm, and he's stretched out on the couch with Bucky wound around him, and it's just. It's very pleasant, is all.
He doesn't quite know what it is that he and Bucky are after that. His weakness in letting Bucky warm his hands under Sam's clothing, right on bare skin, is immediately exploited indefinitely, every time Sam is sitting down or standing in the kitchen or once, memorably, in the middle of a fucking mission. The plastic nanotech in the new arm means it's not metal which means it, at least, is warm to the touch. Sam thinks about this sometimes like it is a tiny blessing, when Bucky is pressing his ice-cold fingers up under Sam's shirt.
After a while he hardly even notices. He's cooking eggs at the stove, and Steve is leaning against the sink drinking a cup of coffee, and Barnes comes up behind him and slides his hands up under the hem of Sam's sweatshirt, leans over his shoulder and hums thoughtfully. Sam scrapes the wooden spoon against the bottom of the pan, folds the eggs in on themselves, leans back against Bucky slightly, and then Steve is clearing his throat and making weird noises and when Sam looks, weird facial expressions too.
"Morning," Bucky mumbles, and peels his hands away from Sam's ribs, and reaches for Sam's mug of coffee like it's no big deal, like there's none in the fucking pot, honestly. They really need to have a talk about appropriate boundaries, like, don't drink my fucking coffee, Barnes.
Steve's weird faces just keep going after that, in many and various ways.
"Is that your sweater?" he asks one day, and Sam glances over at Bucky, and yeah, yup, that's Sam's sweater alright.
"You better not be stretching out the shoulders of that," he says warningly, and Bucky rolls his eyes.
"Wearing each other's clothes?" Nat asks meaningfully, and Sam shrugs.
"It was in the clean laundry," Bucky says, injured, "I didn't know it was yours, Christ, it just looked comfortable," and Sam knows that's a lie because the last time he saw that sweater it was on his bedroom floor the night before last, and Bucky had come in to huddle under Sam's quilt until he'd stabilized, and Sam had wondered, with mingled interest and resignation, if they were gonna wind up sharing a bed the whole night. They hadn't; Bucky had shuffled back to his own room once he wasn't shivering, and apparently he'd picked up Sam's sweater on the way. Sam doesn't want to think about this too deeply.
"Whatever," he says, "if you want to wear it, it's just a sweater." Bucky looks smug, and Nat looks like she's working some things out that maybe she shouldn't work out, and Steve just looks- confused, maybe. Whatever, Sam thinks. Sam was confused for, like, a month. Steve can deal. Besides, his sweater looks good on Bucky. He reminds himself to look up thermal clothing options later, because if Bucky’s stealing Sam’s clothes now he clearly needs more than, like, the three shitty cotton henleys he rotates through. They’re worn at the cuffs, for shit’s sake, and Sam never sees Bucky in less than about eight different layers of terrible sweats topped off with Steve’s terrible knitting.
Later that night, he finds himself buying some ridiculously expensive merino wool knit all the way from New Zealand, just because it promises exceptionally soft, lightweight warmth. Whatever, he thinks again, and puts in the technically-for-emergencies team credit card details, and doesn’t think any more about it.
When it arrives, it turns out it’s totally worth the money, because it’s cloud-soft, the kind of deep slate blue that’s apparently called heather, and Sam maybe wants to touch it all of the time. He leaves it nonchalantly on Bucky’s bed, waits a day or two, and then Bucky shows up one morning wearing it, and Sam’s mouth kind of goes a little dry.
“Hey,” he manages. “Nice sweater.”
“Thanks,” Bucky says, and smirks just enough that Sam knows Bucky knows Sam bought it, but, again, whatever, because holy fucking shit, Bucky Barnes looks exceptional. Turns out, under the eight layers of bad sweatshirt, Bucky is built, and Sam suddenly has a lot of feelings about that.
“I will buy you like five more of those if you promise to wear them every day,” he says without thinking, and Bucky actually blushes.
“It’s- it’s really nice,” he says softly, fidgets with the cuff. “I can’t remember the last time I was this warm.”
“Seriously,” Sam says. “Five more. I swear to god.”
“You just want me to stop wearing your clothes,” Bucky tells him, pouring two cups of coffee and adding sugar to one, sliding it along the counter to Sam, and Sam rolls his eyes, shoves Bucky in the shoulder. Yeah, yes, it’s so soft, Sam definitely wants to touch it all of the time.
Then Sam's on the couch one night and Bucky stretches out, puts his feet in Sam's lap like he does sometimes. Okay, a lot of the time. Sam’s resigned to Bucky basically always being in physical contact with him now, it’s so fine, it hardly even registers. He wraps his hand around the arch of Bucky's foot - freezing as always - and reaches down the side of the couch, pulls out a pair of fluffy socks he'd stashed there for exactly this fucking situation. Bucky sighs a little when Sam tugs them up over his heels, and then Sam's looking up to see Steve watching them and looking all, like, tender and a little confused. Whatever. Sam lays his palm onto the bare skin of Bucky's shin, slides his fingers down into the cuff of the sock, and goes back to his book, absently rubbing his thumb over Bucky's delicate ankle bone.
"Comfortable?" Steve asks pointedly, and Bucky grins, all teeth.
"Yeah," he says, "I'm real cozy."
Sam suspects Steve is maybe angling at something, here, but honestly, if he's not gonna ask, Sam's not gonna tell, and also Sam is truly not sure what to tell. Your best friend has body temperature issues and likes to cuddle is lacking certain nuance, and if he's being truthful, Sam just kind of wants to let this play out. The way Bucky touches him, he likes it. Likes tangling themselves together on the couch, likes Bucky's hands under his sweatshirt, likes gently stroking Bucky's hair until he falls asleep all dead weight giving Sam mad pins and needles. Explaining it all to Steve, it feels- premature, maybe.
At least, he likes whatever it is that they are most of the time.
"Sam," Bucky says, "Sam," and Sam has to fight his way awake.
"What the fuck-" he says muzzily, dragging his eyes open and flicking on the bedside lamp, "what's the problem, cryofreeze?" and Bucky, standing at the side of his bed bundled in a hoodie and sweatpants, shifts his weight.
"I can't get warm," he whispers, teeth chattering, and Sam closes his eyes and opens them again like maybe this is a dream and Barnes won't be there. He is.
"Oh come on, man, I'm in my boxers-"
"I don't care," Bucky says obstinately, "I'm fucking freezing, move over," and the thing is, Sam realizes, it's probably easier just to do it. He sighs very loudly like maybe Barnes will pick up on the message - he doesn't - and rolls onto his back, stares up at the ceiling in the dark.
"Fine," he says, "fine, whatever, fine , come on," and feels the bed dip as Bucky gets in. "If you're gonna steal my body heat you might as well do it properly," Sam adds, "take your sweater off, you'll heat up faster without the layers," and Bucky shucks off his hoodie, throws it somewhere on Sam's bedroom floor, visibly hesitates before leaving his t-shirt on and digging his way down under the comforter. He immediately insinuates himself into exactly where Sam's body heat has warmed the blankets, which means 1) Bucky is curled up against Sam, head tucked under Sam's nose and icy feet slid in between Sam's calves, consideration for personal space be damned, and 2) Sam is in the cold spot.
"I hate you," he mutters into the soft tangle of Bucky's hair, and Bucky snorts.
"I know you do," he replies, and wriggles himself up against Sam, puts one cold hand on Sam's hip. My life, Sam thinks with resignation, and drifts back to sleep.
When he wakes up, it's to discover that Bucky is even closer, his knee wedged up between Sam's thighs and his breath hot on Sam's throat. For once, it actually feels very peaceful. Bucky's breath is slow and even, his palm warm where it's still spread flat over the bottom of Sam's ribcage, and Sam lets himself smile just a little, secretly, to himself.
"Your dick is poking my thigh," Bucky says. Sam considers his options.
"You're in my bed," he goes with, "move your leg if it's bothering you so much. Or go back to your own bed, if you're gonna keep complaining."
"Wasn't planning on it," Bucky murmurs, and then he does move his leg, pushes his knee up higher, and Sam can't help but rock into the friction. Bucky makes a pleased noise low in the back of his throat. Sam doesn't open his eyes, just rolls his hips against the pressure, feels Bucky's breath quicken.
"That's-" Bucky starts, slides his hand down from Sam's ribcage to his spine, trails fingers down the dip of Sam's lower back, grabs his ass. Sam's, like, steel-hard against Bucky's thigh by now, hips moving in an insistent rhythm, and Bucky keeps shifting and shoving against him like he wants Sam to grind into him, and still without opening his eyes, Sam pushes his hand down inside the waistband of Bucky's sweatpants and wraps his fingers around Bucky's dick, squeezes experimentally.
"Jesus," Bucky says, and thrusts up into Sam's hand, all silken heat. Sam strokes, twists his grip a little, and Bucky's breath stutters. "Fuck," he manages, "fuck, fuck," and pulls Sam in harder against him, and everything's so hot, so much body heat where they're touching, that Sam feels like he might burn up or melt right into it.
"God," he agrees, "god, that-" and rubs his thumb over the head of Bucky's dick, gets it slick with pre-come, and Bucky honest to god whines a little, whimpers at the sensation, and Sam's pretty sure he's gonna come in his pants just from the friction and tension of it all.
He opens his eyes, wants to see, and Bucky's face is inches away, his own blue eyes wide and surprised and joyful, and Sam leans in, swallows his moan in a kiss that turns filthy. They're both coming, Bucky pulsing wet over Sam's hand, and Bucky's tongue is in his mouth and they've never even kissed before now but Sam never wants to stop kissing him now that he's doing it, wants to breathe his breath and lie here skin against skin for centuries, Bucky's heartbeat trembling against his own chest, and oh, right, this is what they are, this is what Sam was waiting for, and it's goddamn beautiful, is what it is.
"What time is it?" Bucky asks afterwards, yawning sleepily into the curve of Sam's shoulder. Sam cranes his head to look at the alarm clock.
"Just gone seven," he whispers back, "we getting up or what?"
Bucky flops down heavily against Sam. "Nope," he says firmly, and Sam kind of wheeze-laughs into his hair, because Bucky is a hundred and eighty pounds of solid muscle and thirty pounds of 3D-printed miracle nanotechnology.
"Okay," he gets out once he has his breath back, "fine, whatever, but Steve's coming by in twenty for our morning run."
"Nope," Bucky says again, insistently, and wraps his arms tighter around Sam's midsection. Even given all the aggressive body-heat-seeking closeness, Sam wouldn't have pegged Bucky Barnes to be such a post-sex cuddler, but you know what, this is okay. It's pretty nice, actually. Sam closes his eyes, drifts back into a quiet doze, and it feels like maybe thirty seconds have gone by when Steve’s knocking at his door way too loudly.
“Yeah, I’m gonna skip it today, man, you go on without me,” Sam calls, and there’s a pause before Steve replies. Bucky fills the gap by opening his eyes, smiling beatifically at Sam, and Sam can’t help but smile back. Bucky’s hair is pretty tangled, caught in strands across his face. Sam tries to smooth it out, and just winds up stroking it, and Bucky lets his eyes flutter closed again.
“Have you seen Bucky?” Steve asks, a note of concern in his voice, “his door’s open, and he’s not in his room, I just-”
“Maybe he, uh, maybe he went for a run?” Sam suggests, frowns at Bucky. Bucky, helpfully, pulls the covers up to his chin, mouths what? at him. Steve, from behind the door, snorts.
“A run? Have you ever met the guy? He’d stay in bed until midday if he could get away with it,” Steve says, and Sam smirks at Bucky, and then Steve opens the door, and there’s a long pause as they all assess the situation.
“Hey, Stevie,” Bucky says first, gives him the most shit-eating grin Sam has ever seen, and that’s Sam’s cue to close his eyes, pull the covers right up over his head and let the two of them sort it out, except that Steve just makes this clearing-his-throat noise for way too long and Bucky, that shit, doesn’t say anything at all. When Sam emerges from under the covers again, Steve’s making that weird face again, and Bucky’s just smirking, fuck, Sam’s never having sex with him again if this is how he’s gonna be.
“Steve,” he says, as dignified as he can be under the circumstances, which is really not very, “hi.”
“About fucking time,” Steve says, “Jesus Christ, I’ve been waiting for the two of you to bunk up already for literally months, I can finally get Nat to pay up,” and Sam pauses for a minute to consider this before finding the first thing that comes to hand and throwing it at Steve.
“Captain fucking America, huh,” he says, as Steve dodges Sam’s alarm clock, “go on, get out, go for a fucking run, leave us alone.”
“Yeah,” Bucky agrees, “leave us alone so we can make some noise this time,” and Steve goes a little pale and then bright red and then, mercifully, leaves, shutting the door behind him.
“You’re the worst,” Sam tells Bucky, “the actual worst, I hate you, fuck, he’s my best friend.”
“He’s been my best friend since 1933,” Bucky points out, “he’ll cope,” and then he’s sliding closer, hands on Sam’s hips and pulling him in, and wonder of wonders, his hands aren’t even a little bit cold.