Wooing Robert Downey Jr.

Making a Captain America movie was not part of Robert Downey Jr.'s overall contract with Marvel Studios, so the Russos were tasked — with Feige's support — with persuading the actor to sign on to the project. The stakes were high: Without Stark, Civil War was a no-go.

According to the Russos, it turned out that what had so excited them creatively about Civil War excited Downey, too. "I think he loved the fact that we were going to deconstruct the genre by having a third act where the two heroes are having in essence a life-or-death battle with each other," said Joe. "He was really attracted to the fact that we were going to make his character much darker in this than he had been in any other film up to this point."

Indeed, while Downey's face is as prominent as Evans' in the Civil War posters, the fact that this was a Captain America movie afforded Downey an unusual opportunity, one the Russos first experienced at the onset of their career. "[George] Clooney had a small role in Welcome to Collinwood, and he kind of helped the movie get greenlit by doing that," said Anthony. "We said to him, 'Oh, thanks so much for doing this role, sorry it's so small.' And he goes, 'Look, guys: This is the most fun for me. Playing the lead kind of sucks, because your job as a leading man is to show up and let everybody else steal the scene. Now I get to steal the scene. That's really fun for me.' I think Downey had a bit of that. Because Chris was the titular lead of the film, he had license to go off the rails a little more than he would as a typical lead."

But that did not mean that Downey was content to coast through the making of Civil War. The actor's involvement was officially announced at a Marvel Studios media event in October 2014, and right up through production, Downey met regularly with the Russos and screenwriters Markus and McFeely — none of whom had worked on a film involving Tony Stark — to develop the character of Iron Man in Civil War. "There's a process you go through with Robert where you work on the scenes the week leading up to shooting them," said Joe. "Whatever scenes are coming up, we'd go over to his house on a Sunday, we'd all have lunch together, and work on the scenes. We would rewrite them based on ideas that Robert had about the character, because he knows the character better than any of us ever will."