Different anon, but what if, for maximum trash purposes, after Steve falls from the hellicarrier, he's REALLY hurt, and a still-confused not-quite-Bucky feels compelled to save him by jerking off into a barely-conscious Steve's mouth. Steve wakes up in the hospital later with Bucky's taste in his mouth and confused by his flashes of memory, if he's mixing up his old memories with the present or all of that oxygen deprivation has messed with his mind.