Before Iron Man, Robert Downey Jr. was a punch line for any celebrity rehab story. Now he's considered the mastermind of the greatest comic-book movie ever. Well, for a couple months until The Dark Knight opened.

Going into Iron Man 2, Downey is playing the humble card. "I also have to let go, because there's an aspect, particularly after the success of things, I noticed my narcissism got dialed up," said Downey while promoting his latest film, Tropic Thunder.

"Suddenly, for a minute, I felt like everyone needed to take a knee and listen to what I had to say, because I f--kin' made it, and my way works and all this stuff. Then I go home and I go, 'Oh my God, what's happening to me? I gotta get grounded here.' "

Downey got Tropic cowriter and actor Justin Theroux the gig writing Iron Man 2. Theroux is just crawling out from under the pile of Iron Man comics as we speak.

"I've just stopped marinating in all the Iron Man lore that I didn't know, and I'm sort of firing up the chainsaw and ready to attack it," said Theroux. "You're writing for Robert Downey Jr., so, at the end of the day, that's an enormous amount of fun."

The new collaboration has Downey all fired up to slip into the gold suit again. "I'm stoked," he said. "I'm into it. I'm excited to do another Iron Man right."

I'm stoked too. I'm also pissed that he is stealing my schtick.

No doubt you're referring to Downey being in and out of rehab.

I'm excited to do another Iron Man right.