When asked how he felt being the antagonist of the film, Downey shared, "It didn't bother me at all. I've always thought of it in some ways that Tony is the antagonist to himself in his own story, so this isn't a problem. This guy understands problems 'cause he is a problem. And he tends to create problems."
However, that doesn't mean he disagrees with Stark's stance in the film. "I wholeheartedly agree with what he does in this... Which is, by the way, more than I could say for some of the other movies."
"Alls I'm saying is ultimately he's never been in a status position over Cap," he explained of Stark's relationship with Steve Rogers. "It's a crappy deal for Tony. It has been from the time he came out. I think he's actually been pretty civil, all things considered. When he tries to bring lightness into the fact that he actually, at certain points, has the real upper hand; he just can't help himself. Because it's just been simmering for years and it's very unrequited."
Captain America himself Chris Evans has a few other ideas about their relationship. "I think they're very different men but this is the beautiful thing about family," Evans said. "In a family you know you could hate your mother, you could hate your sister but you're my family and we have to make this work. I like the end of 'Ultron,' when I say, 'I will miss you, Tony' and there is a love and respect there."
According to Downey, Stark's position will also have to do with where the character sees himself fitting into the world post-"Age of Ultron." "He's thinking about where he went to school. He's thinking about his folks. He's thinking all this dough he inherited wasn't really just meant for him and he should be trying to do something with it," he shared. "He's not a kid anymore. He's thinking about the back nine."
"He's really trying everything from great earnestness to outright manipulation, emotional manipulation to try to get Cap to just make this, to swing the vote," he added.
Audiences have seen a lot about Stark's father Howard, but what of his mother? Downey shared his thoughts on her, saying, "I'd always felt that she was a really cool kind of Ivy League rebel, an Eleanor Roosevelt type, you know? So that's kind of what's been on my mind with it."
Downey and Evans are joined in the sequel by Scarlett Johansson, Sebastian Stan, Anthony Mackie, Paul Bettany, Jeremy Renner, Don Cheadle, Elizabeth Olsen, Paul Rudd, Chadwick Boseman, Emily VanCamp, Daniel BrÃ¼hl, Frank Grillo, William Hurt and Martin Freeman.
"Captain America: Civil War" opens May 6.