Each took his own path to discover who their real characters were.
"You sort of want to be the person (you're portraying)." Foxx explained. "I got a chance to go down and watch (former Clevelander) Nathaniel Anthony Ayers from a distance without meeting him because, a lot of times, when people meet us they'll be on their best behavior and they'll change it up.
"I just wanted to see him in his own element, how he ordered his food, how he talked to people and -- within five minutes -- you would've seen four different sides of this guy. He was happy. He was angry. He was jubilant. He was all these different things.
"So, by doing that," Foxx went on, "when you're doing a character, you want to do the nuance. I dropped some weight, got my hair done nicely and then I got a chance to meet him and I filmed him on my phone while he was talking, just to capture some of those little nuggets.
"It was also scary to play someone schizophrenic. We're all artists and we all go different places in our minds. I feel this way: if I were to lose my mind, I would lose everything. So, there was a little bit of a fear going into the project, but that was it. You just had to get it and once you do you feel like it's really that person. You'll say it in your mouth; you'll say whatever that person says and hear it in your mind. Then you say, 'OK, I am that person.' "
As always. "Iron Man" Downey took a much less personal approach to re-creating the persona of Los Angeles Times columnist/author Steve Lopez. "We had a cigar together and we talked. He wanted to tell me that to impersonate him would be to do a disservice to the movie. But, I mean, it's different every time.
"I knew that the technical prowess and the degree of difficulty was going to fall on Jamie and that I was to observe and report on that as though I were an audience member. (Director) Joe Wright said that it was really important that I do next to nothing and listen a lot, which is very counter intuitive to my kind of ectomorphic disposition. So it was an equal challenge for me in that way.
"I had a couple of ideas," Downey said. "I thought that my hair should be short and the next thing you know (co-star Catherine) Keener is shaving my head in the first day of rehearsal with a number two scissor blade. Then we had three weeks, I think, of rehearsals which is unheard of.
"Joe came off the heels of 'Atonement' and the buzz of all that. I think that he went and got his BAFTA in the middle of while we were shooting, but above that we kind of represented the Hollywood -- I don't want to say establishment -- but it was like, 'Great. You're really good and we're making a movie in L.A. about L.A.'
"I think (Wright) opened our eyes and we opened his eyes and we all wound up becoming this kind of third thing which was centered around what Jamie was going through and what he was trying to communicate."