I meant for this to be a small drabble of perhaps 200 words, but it got away from me. :/ Oh, well. :)
...
Bucky – or rather, the Winter Soldier – had always been observant. He had to be, for him to be able to do his job right. Even after he broke away from his conditioning under HYDRA and began living in the Tower with the rest of the Avengers, he hadn't stopped his careful watchfulness of everyone there. When he entered a room, he immediately, unconsciously, looked around the room to scout for entrances and exits, weak spots in defense, and places that were the best to take cover, should anything get through. He sat with the best vantage point of the room, watching as everyone went in and out in the midst of their daily activities.
It was something like muscle memory, he supposed. And he could admit that there was some paranoia there as well, because seventy years of being controlled by the Russians and by HYDRA would do that to anyone.
So he'd had some time to watch the other members of the team. He knew that Natalia – no, Natasha; she has a new name now – would sit somewhere with a book when she was tense or upset, and would watch the room and the people in it in much the same way Bucky did.
He knew that Clint hated the color blue, and would come out to the communal kitchen and stress bake when he woke up in the middle of the night from a nightmare. He made the best meringue, too.
He knew that Steve still struggled to find a place in this century, and was only ever really calm when Bucky or Sam was with him.
He knew that Bruce thought very little of himself, and apologized for things that weren't even his fault, and he liked Natasha but had no intention of doing anything about it.
He knew that Sam found purpose in caring for people in ways so subtle that hardly anyone realized he knew they were upset and was doing something about it; he'd make hot chocolate and then claim he'd made too much and would demand that the melancholy person help him drink it, or he would pull someone into watching a movie with him on the couch, cheering them up by either throwing popcorn playfully at them or sitting in silent support beside them.
He knew that Thor was a little shit who liked to pretend ignorance on 'Midgardian customs' just so that he could get away with whatever awkward thing he wanted.
He knew that even through Tony's façade of pretending not to care, of claiming the arc reactor the best of all of his inventions, that he actually hated it with a passion. Not so much the work, because he recognized that the work was amazing, and it powered his Iron Man suit – which he could never not be proud of to some degree – but he hated that he needed it. He hated how he had to have the light sticking out of his chest, a constant reminder of how he'd gotten it and the person he'd been before.
Tony hated who he'd been before; that much was clear. He hated how the person he'd been before was so painstakingly documented that it was something that he could never escape from, that no one would let him forget. He wasn't a playboy anymore, but the very day the press had found out about his and the Winter Soldier's relationship, there were already several people speculating how long it would last, and how long the statistical likelihood of him cheating on Bucky would take.
And Bucky hated to see Tony so upset, hating himself. He knew all about self-hate, and could understand to some degree why Tony would despise the foreign object sticking out of his chest, there and obvious for the world to see. He knew how Tony showed it off, letting the light shine through his shirts like he was proud of it, because he didn't want someone else to shame him for it. No one made a big deal about what someone wasn't trying to hide, after all.
Bucky did the same thing with his arm.
He hated his metal arm. It was a product of the Russians, used to kill people – innocent people, and he remembered them all. It was a reminder of all of the bad things he'd done, a reminder that worked not dissimilar to Tony's arc reactor. Tony had made a better arm for him, an upgrade, but still the reminder of what a metal arm was capable of stayed with him. Tony had painted Steve's shield where the red star had been before, saying how it showed everyone what side he was on, and damn anyone who said otherwise, but still Bucky remembered the red star that had been there before whenever he looked at it.
But he kept it visible, didn't try to hide it. He didn't have the whole arm exposed up to his shoulder as he had in his days as an assassin, but he didn't purposely wear clothes that would hide the arm, either. Tony had made a synthetic glove for the arm when they had to be stealthy, but otherwise Bucky didn't bother with it.
But even as much as he understood Tony's feelings, he still appreciated the arc reactor. It was what had kept Tony alive long enough for Bucky to meet him, and continued now to keep him alive. In the beginning of their relationship, when they began to share a bed at night, Tony would hide it self-consciously, not liking the glow it gave to the room. Only after Bucky had said he liked the light, because he hated the darkness, and the light coming from Tony made him less nervous – only then had Tony tentatively begun to leave his chest uncovered while they slept.
And then one day, while giving Tony a forehead kiss in greeting, he got the idea. He loved every part of Tony, of course he did. He ought to show that, shouldn't he?
So when Tony got that look on his face, that expression in his eyes that said he wasn't in a good place mentally, Bucky casually leaned down and kissed the arc reactor through the shirt. Tony had startled obviously the first time he'd done it, giving Bucky an odd look, but Bucky pretended that nothing was different and pulled him into a discussion about his tech. Tony was always willing to talk about tech.
After some time, Tony began to accept the seemingly random kisses to the arc reactor. And sometimes, they were random. Bucky was just as likely to kiss Tony's cheek as he was the arc reactor.
After several weeks of this, Tony had finally mentioned it, joking – (not joking) – about how Bucky had developed a fixation – a kink – for the glowing light in his chest. But Bucky saw the vulnerability, the uncertainty, in the other man's eyes, and he knew that Tony was trying to ask him in his Tony-way why he was doing this.
So Bucky told him. He didn't blurt out all of his thoughts of course, because he knew that Tony hated feeling vulnerable and exposed, and while the billionaire knew at least subconsciously that Bucky knew him intimately and could read him, it wasn't something that they ever actually brought up. Bucky knew him better than that – knew that it was something best left unsaid.
So Bucky simply stated that the arc reactor was what kept Tony alive, showed that he was still alive and real and there, so even though he knew the scars sometimes hurt, he was still grateful to that little circle of blue that said he was safe.
And Tony, genius that he was, could read well enough between the lines. It was better when Tony came to these conclusions on his own, so Bucky said just enough for Tony to realize that Bucky knew about his insecurity, and he was trying to show his love for him in that small way.
They didn't talk anymore about it, but a few days later, when Tony joined Bucky in the shower, the shorter man kissed his metal arm, right over the star. And Bucky startled, the soap slipping out of his hands, before he smiled back at Tony and pressed a grateful kiss to Tony's lips.
Bucky understood.
