The first 5 times Bucky gets the pleasure of seeing Tony's wings are each memorable in their own way. But the first time he really got to see Tony was even better.

Bucky knew all about self-hate, and could understand why Tony would despise the foreign object sticking out of his chest, there and obvious for the world to see. He knew how Tony showed it off, letting the light shine through his shirts like he was proud of it, because he didn't want someone else to shame him for it. No one made a big deal about what someone wasn't trying to hide.