Originally played by Terrence Howard in Iron Man, Don Cheadle replaced the actor as War Machine in Iron Man 2. He eventually made an appearance in 5 more MCU films and became a prominent character. Recalling the time he was offered the part, the actor says he had to make the decision in quite a short amount of time.
"I was actually at my kid's birthday party—a laser tag party—and I got a call from my agent," Cheadle told The A.V. Club. "And they said, ‘Hey, so I want to connect you to these Marvel guys. They want to talk to you, but they want to offer you the part.'"
"I don't think it was [Kevin] Feige. I don't know who was on the phone. But they said, ‘Hey, this is the role. We want you to do this. It's a six-picture deal.'" he added. "I was like, ‘What?! Oh, uh, okay…' And I'm trying to do the math. I'm like, ‘That's 11 or 12 years. I'm not sure.'" He was then told that if he doesn't say yes or make a decision in an hour, they were going to move on to the next person.
"An hour to decide 12 years, and a role and parts that I don't even know, in movies that are coming down that I have no idea what they'll be," Cheadle added. He told the studio that he's at his kid's party, so they were kind enough to let the actor make the decision in two hours, which Cheadle says is "generous" of them. He then went back inside the laser tag place, and was discussing the role with his wife. Cheadle's wife told him that if he wanted to do something like the MCU films, which he has never done before, then he should take it.
Of course, the actor did end up making that choice and has made a huge turn in his life. Making a big decision like that isn't easy and certainly takes time, but taking up the War Machine role surely paid off.
For now, Cheadle's next MCU appearance is still unknown but it's likely that we haven't seen the last of War Machine.