Summary: Stark had thought he understood why Rogers had done it, why he had chosen Barnes over him but wathcing Rogers now, Stark knew he understood nothing of Rogers'choice.
I wrote this before I actually saw Infinity War but even still I like how it turned out so I'm posting it.
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He looked broken. There was no other way for Stark to describe that look, Rogers looked destroyed.
He didn't smile, hadn't since their defeat. He didn't laugh, in fact he hardly made a sound at all. If Stark hadn't known better he'd think Rogers had been the one to fall to dust.
They'd been working nonstop trying to regroup and re-strategize, and Rogers volunteered for every suicidal mission they came up with, it was almost a surprise when he returned each time.
Stark could hardly stand looking at the man, he could tell how unhealthy the man was becoming, always handing their meager rations off to someone more hungry, younger, smaller. No one had seen him eat more than a handful of bites and it showed but Rogers wouldn't hear of them telling him to eat, ignored them on the best of days and just wandered like a ghost calling out to Barnes on the worst, there was never an answer and they chose to ignore the muffled sobs that echoed through the night from Rogers' sleeping area.
Rogers was the last to sleep, the first to wake and Stark could see whatever had been left of him dying a little more each day.
Of all the people Stark expected to die in their final attempt at defeating Thanos Steve Rogers was number one on the list, then again Rogers had died with Barnes, all that was left was for the body to catch up with the soul.
Stark had thought he understood Rogers' reasons behind choosing Barnes over their friendship, but watching Rogers call out to Barnes once again he had to admit he hadn't known how deeply Rogers had loved Barnes, what it must have meant to learn that the other man was still alive, that he'd been used and tortured for so long, Stark didn't know what it was like to have your life returned to you or how far you'd go to protect it when it was and looking at Rogers' stricken and tired eyes Stark was almost glad for that.
Maybe, if the universe was kind, Rogers would find Barnes in the afterlife. Stark couldn't bring himself to actually believe that the universe would finally take pity on Rogers but he could hold a single spark of hope that it would.