He's remembering little things, drips and drabs that mean nothing in the long run but everything here and now. Like how Natasha will only drink coffee if it's gone pale cream with milk and as sweet as can be (he think it says something about who she is, the way she likes her coffee so sweet) or how to calm Bruce with a smile and a gentle hand on his shoulder. Clint and Thor are easier to figure out, offering up information at the drop of a hat, eyes eager and excited when he realizes he already knew that.
Tony, on the other hand...
There's something about Tony Stark, something other than his brash abrasiveness or his sly humor, something vulnerable about him that speaks to the little guy from Brooklyn Steve remembers better than these larger than life personalities. And he's noticed, the few times he's actually seen the man outside of his lab, that Tony's default expression is... sad. Almost unspeakably so, with eyes half-lidded and longing, the expression of a man in desperate need of something he feels he might never find. It baffles Steve, how a man so obviously on top of the world seems to be so totally without anything to hold on to.
His life is a constant puzzle now, questions and answers and mysteries one after the other, and it's all he can do to follow the breadcrumbs left around the mansion. Oh, he's not afraid to ask when he's bothered by something, but he likes to figure things out for himself, since sometimes the answers are completely different from his expectations. Relationships, for example, are particularly hard. Clint and Natasha are as close as he's ever seen a man and a woman, but they've told him time and again they're not together and there's a ring of truth in it each time. Thor and Clint pal around as much as Steve and Bucky did, but Banner's the one Clint seems closest to. And Tony is an enigma wrapped in a mystery, all tied up with daddy issues and insomnia, compounded by his outright refusal to meet Steve's eyes and Steve has no idea what to do with that, honestly.
So, he follows the breadcrumbs.
He leaves cups of coffee on the workbenches in Tony's lab. He makes friends with the robot helpers. He forces Tony to just stop sometimes, whether for a sandwich or a breath of fresh air, and the approval in everyone else's eyes makes it worth the while (even if Tony still flinches away from Steve's hands). He doesn't force anyone to do anything for him, begs them to carry on as they always have, and he learns to pick up the pieces.
One night, Clint makes a four-course Mexican feast and Steve drags Tony out of the basement to join the meal, purposefully ignoring his complaints and focusing on the too-sharp cut of bone under his skin and the manic, half-caged glint in his eyes. It starts out stilted, all awkward conversations and in-joking that Steve still doesn't remember, but it grows comfortable as food disappears and they all relax. It's something Steve can't remember them doing, this family-style meal together, but it feels familiar. He smiles, happy and carefree for the first time in forever, turns to see if Tony's feeling the same, and it hits him like a hammer blow to the chest.
Blue light spread soft across the sheets of their bed.
Tony's face is wide open, eyes soft and longing and happy-sad in a way that steals Steve's breath. He doesn't look as weighed down or lost as he has recently, looks younger almost, as he studies the happiness on Steve's face. And a couple more pieces slot together, a couple more memories unlock.
Tony with his head thrown back, laughing as Steve crows over finally beating Clint at Mario Kart.
"Tony," Steve breathes, images filling his head, one after the other, Tony in all manner of moods, from anger to anticipation, sadness to lust. All directed at Steve and all carefully hidden now in his eyes.
"What?" Tony jumps, eyes closing off, staring at Steve with an expression of almost-horror on his face that leaves Steve tongue-tied. Out of the corner of his eye, Steve sees Natasha gesture, sees Clint shake his head quickly, eyes darting to Tony and back. He thinks they might actually mean him to see, but he doesn't care, he's found another piece of who he was before all of this and--
"It's times like these that I wonder what I ever saw in you," he hears himself growl, feels the frustration and helpless anger. The context is still gone, though, leaving him only with the resolve to never have something like that happen again.
"Nothing," he blurts, breaking the tense silence that's fallen around the table. Tony's relief is not only visible, it's palpable and Steve wonders again at what they'd had, at how something so wonderful (he remembers the glow on Tony's face, the consistently comfortable, relaxed set of his shoulders, he knows it was wonderful) could go so horribly wrong. "No, I-- I'm glad you're happy." He stops, smiles, and cannot help himself. "You always look so sad."
The wonder on Tony's face and the approval everywhere else settles something, gives him a purpose.
Steve Rogers may not know all of where he's been, but he sure as hell knows where he's going.