His resurrection has all the characteristics of an origin story for a Hollywood superhero: A gifted young actor loses his way, cheats death again and again, then straightens himself out just in time to conquer the world. But the way Robert Downey Jr. tells it, the reality involves a lot more detours, and the final act still hasn't been written. With Iron Man 3 poised to extend his outrageous hot streak, Downey invited GQ's Chris Heath to his house in Malibu to talk about where he's been, where he's going, and where all the demons went.

Robert Downey Jr. habitually carries with him a miniature brown leather suitcase. If he's rummaging inside it, it's usually for another square of Nicorette gum, but there's all sorts of stuff in there: rattling pill bottles—antiparasitics and antivirals ("Sushi's worth it, but sometimes you've got to clean the bugs out") and some kind of chemical if he happens to eat bread—a dark blue beanie bearing the logo of the security company that guards this Malibu estate, some medallions whose twins I'll later see his wife, Susan, wearing, and a typed letter he recently received from Woody Harrelson onto the back of which he has, perhaps absentmindedly, been pressing chewed globs of gum. There is also—and this is what he removes now from the case to show me—a solid-gold Iron Man helmet head.

Downey holds in his hands the head of the character who set his life on a new trajectory and examines it.

"It is funny, dude," he says. "I do contemplate this thing."

Downey commissioned a jeweler to make a set of these heads as gifts for crew members when Iron Man 3 wrapped, but he kept one for himself and it is now his to ponder at his leisure. "There's some sort of strange message about something in there," he says. "Just about masks, and what people create. I still haven't figured it out. There's no rush."

Downey remembers staring at an image of that stoic gleaming helmet, as he tried to work out what it would take to be the man inside it, when he was preparing for his Iron Man audition in 2006. It is easy to forget what a strange place Robert Downey's career was in back then, and not just because of the long trail of upheavals—the drugs, the guns, the arrests, the rehabs, the prison sentences—that could have destroyed it.

For years, whenever Downey appeared on TV, he was routinely introduced as "one of the greatest actors of his generation." (Downey's demeanor on such occasions suggested that such statements expressed a truth so obvious it barely needed repeating.) What was less apparent, until you looked with a cold empirical stare at the whole sweep of his career, was that he was also one of the least successful actors of his generation, almost unbelievably so. The biggest hit he had ever been in was the long-forgotten 1986 Rodney Dangerfield comedy Back to School, which came out when he was 21. After that, no matter what fanfare each new movie arrived with, and no matter how often Downey's own contribution would be highlighted, it was disappointment after disappointment. His two best and most notable performances in those years were in Less Than Zero and Chaplin, but both were commercial flops. When he chose movies so commercial that their success seemed predestined—Air America in 1990 with perhaps the biggest star of that era, Mel Gibson; The Fugitive sequel, U.S. Marshals, in 1998—the rebuke of their failure seemed almost humiliating.