Can you imagine in civil war Tony confronting Bucky about killing his parents? Can you imagine the heartbreak?
See, I think Tony would be so focused on catching Bucky, on making him pay, that when it finally comes down to it and he finally sees Bucky, sees how frail and pale he is, how his metal arm is starting to rust, that he’d really stop and pause?
Like how could this man, who looks like he’s one missed meal away from keeling over, have killed his parents?
And then it hits him. This man didn’t. The Winter Soldier did. He hadn’t really understood until he saw him that they really are different people.
Cue Tony Stark bundling Bucky up into a Quinjet. Bucky assumes he’s being arrested, but instead Tony drops him off at Steve’s apartment with a new arm he made on the way back and a fake identity so he can live under the radar.
Tony then goes home and drinks until he passes out.