Nat realizes it first. She’s known Steve better than the rest, after all. She wonders why she didn’t know it sooner. It clicks when she sees Steve and Bucky training one morning, the radio playing an old song as Bucky ties his hair back. She watches the way their bodies move together unconsciously, somehow deflecting each other and yet being able to fight together like they were one, the way they just fit. And when Bucky tackles Steve to the ground and grins as Steve throws a punch, she can’t compare it to the way she and Pietro train, or Wanda and Clint, and she looks away because she knows its different when it comes to the two of them.
Sam realizes it next. It’s a cold morning and he doesn’t want to run down the street to the café to get breakfast, so he drops by Steve and Bucky’s apartment just as it starts to rain. After raiding their fridge, he hears low whispers coming from the bedroom opposite and he peeks through. And as he watches the two of them talk, hands intertwined, he’s glad the rain makes it hard to make out what they’re saying, because this feels real, too real for him to be listening in on. And he feels his heart ache at the thought that Steve finally has someone that he can love without any hesitation. Someone that he trusts completely. Sam closes the fridge and locks the door behind him before either of them get up.
Wanda sees it next. It’s almost painful once she realizes Nat and Sam were the only ones that knew, but she took what she could, and shot them glances here and there whenever it got particularly obvious. She got a smirk and knowing shrug from them as Steve and Bucky argued in the living room one afternoon. They’d been at it for hours, and even though she wasn’t listening to most of it, she guessed what it was about. What it was always about. She heard Steve yell that Bucky wasn’t like he was before and she heard Bucky yell back that he didn’t know that. She knew it would end like it always did, too. One of them would stop, throat scratchy and tired, and the other would wrap themselves around them tightly, and all their broken pieces would come together. Their auras were pulsing, she could feel it, their souls fighting to be closer, and it drove her mad that it had taken so long for her to see what the others hadn’t yet. She smirked to herself, later that night, because maybe Steve and Bucky hadn’t figured it out yet, either.
Pietro realizes by accident, when he’s running past the kitchen for a snack and Bucky’s tying an apron around Steve’s waist and he rests his forehead on his shoulder as his fingers knot. He almost stops completely in his tracks, but recovers, moving a bit slower so he can catch the rest of the scene. He doesn’t need to, though, because once Bucky’s head is back up, he sees the expression on his face as he watches Steve grin. Pietro knows that look. He’s seen it a million times before; on Nat’s face when Clint makes a stupid joke and she has to pretend she doesn’t want to laugh; on Tony’s face when Pepper bosses him around and he has to pretend to be sulky about it; on his parent’s face, years ago, when they were alive and had themselves to live for. He rushes away without getting anything to eat, his stomach twisting with the unsaid longing to find someone he’ll look at like that, too.
Clint realizes when he catches Nat and Wanda gossiping one night over a bottle of wine and blaring music. He squints at them when they laugh after he asks why they said “Bucky” and “marry America” in the same sentence. It takes him a nap and a few slices of pizza to mull over, and when he finally has a guess, Nat laughs and asks him what took him so long. Of course, he sees it now. It’s in the way they look at each other, the way their eyes get brighter, the way their hands always seem to find each other’s, the way their voices somehow only seem to be for each other when they’re talking. It’s in the way Steve looks at Bucky the next morning over coffee when they’re all down at the local café having breakfast, and Nat and Wanda are too hungover to return his look, and the way Bucky smirks “what” teasingly when he catches him. Clint makes a note to knock the next time he stumbles into their apartment without warning in need of a couch to sleep on.
Tony sees it when they’re all fighting to share a couch one Friday night at the Avengers headquarters before they watch a movie. He wonders how long it’ll take them to actually pick a movie after this is over, when he sees Bucky’s hand trail to Steve’s waist and pull him in so he’s practically sitting on top of him as Pietro and Clint shove each other away so they can get the corner. He looks at the way Steve practically melts into him as he leans back, their hands finding each others’ and the way the smile on his face still hasn’t left even after the movie’s over and Clint’s tearing up about how much room Rose had on that door and Bruce is arguing that Jack would’ve still froze to death anyway. Tony turns the TV off and watches as everyone goes to bed one by one, until they’re the only ones left and Tony pretends to be fixing the DVD player as the both of them finally get up, hands still locked together.
Steve thinks he must’ve always known that Bucky was the only one he’d give it all up for. He thinks that the moment he dropped his shield, was the moment he knew there was no going back. And he didn’t want to. He’d gladly let Bucky kill him if it meant he didn’t have to see a world where he and Bucky weren’t right. But Bucky had saved him, and he thought that maybe, the hands he felt on him in the water, sliding over his body and gripping his waist tightly, was a sign that they weren’t done yet. Maybe the trembling fingers that moved over his face as he lay semi-conscious on the riverbed were trembling from fear and not from the cold. And maybe, when he had woken up for just a second, maybe he knew that the figure walking away from him would come back to him eventually, and he blacked out for the second time, this time knowing that Bucky wasn’t walking away.
Bucky knows all of it, now. He knew it somewhere inside all this time, but the fact that he remembers is what keeps him grounded. Makes him believe that he’s not making it all up. He remembers nights in their tiny Brooklyn apartment, when Steve would get sick and they’d share a bed for warmth, and he’d lie when he woke up about Steve taking all the covers. He remembers knowing how he felt when Steve turned eighteen, and the fireworks that made the night explode into colours were nothing compared to how he felt when Steve called his name. He knew when he fell off that train, that Steve would never forgive himself for letting him go, but he tells him on bad days that even though he fell the first time, he jumped after him the second, and something about the way his fingers reflexively let go, told him that this time, it was right.