[ Well that first reason is a nice little buzzkill. Some stupid, long-underused part of him that could hope had hoped for altruism, as unrealistic as that might sound. But of course, the most glaringly obvious thing comes first. Stark is a problem-solver, and now a diplomat, apparently.

The next one, he wants to say something, explain that he gets it, Stark just learned that his best friend Captain freaking America kept things from him for the sake of his assassin best friend. Hell, Zemo even made the guy watch Bucky do it. He can't say he would have reacted differently under the same circumstances. Bucky keeps his mouth shut, because Stark is still speaking, and it's important.

Bucky has to keep himself composed for the third reason, because he hears 'mom' and his heart feels like it got stabbed with a dozen knives. He remembers the idea of his own mother, but can't place her face, or the last thing he said to her before he shipped out. It has to have been "I love you," but that memory is long-gone. God, what she must have gone through, knowing her son was missing-- probably KIA. She would have been humiliated if it came out that she was the mother of the Winter Soldier.

Stark's mother, on the other hand, would be proud of her son, what he became. And Bucky took that away. He presses his lips together, moves his hands to his lap as his chest tightens. ]

I'm sorry for what h-- for what I did. I know it won't fix it, or bring them back, but I want you to know that. I'm really sorry, Tony.