I saw a post on tumblr talking about the mechanics of Bucky's metal arm---it stated that for the prosthetic to be as integrated with his body as it apparently is, Bucky would need to be on strong immunosuppressant drugs in order for the device not to be rejected and attacked by his system. Because of this he'd also need immune boosters so every little germ doesn't settle in and ravage him. The result? Bucky rarely gets sick, but when he does, it's bad. I'd like to see Steve's reaction to finding this out, maybe once Bucky's out of danger some teasing about their old roles being reversed re who takes care of whom.