RNG'd 21
They said Captain America went down into the ice. It was the stuff of legends. Good vs. Evil and all that. He'd died a heroes' death and served as an exciting tale of the past as time went by.
Only he hadn't stayed down there. He'd been fished out along with Bucky, pulled from the ice by the people they'd fought to defeat. They tried to twist them to serve HYDRA's cause, and eventually Bucky's mind broke to the brain washing. Steve watched his friend turned into a puppet assassin, an asset. Over the years there was less and less of his friend, and long stretches where one or the other of them was kept away in cryo.
And then he woke up again to find Bucky gone, only this time, no amount of time brought him back. He was alone. And he stayed that way for longer than he could count, days blending into years, prisoners coming and going. When Stark was captured Steve didn't expect he'd be around longer than any of the others. He'd break or he'd die. There wasn't much point in getting to know something that would be gone in a matter of time.