THEPERFORMANCE

AT first glance, Nick Stahl’s James Reedy -- an aimless 30-year-old who serves as the central character of William Maher’s “Sleepwalking,” out in limited release Friday -- doesn’t seem to do much of anything. He lives in a bleak industrial Northern California town, toils at a menial job and keeps his words to a minimum.

But Stahl says there’s more to James than meets the eye. “Some people read the character as being kind of slow or mentally deficient, but to me, he was someone who was really damaged, a victim of abuse,” says Stahl. “James ended up retreating from the world and was just kind of beaten down, learned to settle for things and accept a very simple role in life.”

That role changes after his tempestuous sister Joleen (Charlize Theron) blows into town and holes up in his apartment, 11-year-old daughter Tara (AnnaSophia Robb) in tow. Before long, Joleen takes off, abandoning Tara, and James has no choice but to care for his niece and come to terms with his own haunted past in the process.

Stahl says it was the realism in Zac Stanford’s screenplay that attracted him to the part. “I liked the idea of the family dynamic, that things weren’t black and white,” he says. “There was an opportunity to really comb through the layers of the character and expand what was on the page.”

A former child actor who appeared in his first film at 10 and moved from the Dallas area to L.A. at 16, Stahl credits a supportive mother and an intense acting focus for getting him through his more impressionable years. But he speaks with the wariness of someone who’s grown up in a sometimes harsh limelight.

“It was just very weird for me,” he recalls. “I never really had a stable group of friends, and then [in Hollywood], you’re around all these adults, and you can’t really be a part of that, either. It makes perfect sense to me why a lot of people who start out as kids in this business tend to have problems in their life. I mean, it’s a really unusual way to grow up.”

He admits that his own experience made him very protective toward his young “Sleepwalking” costar, Robb, during last winter’s shoot in the Canadian province of Saskatchewan: “I felt I could relate to Anna in a lot of ways.”

Now 28, Stahl has made the transition into adult roles, specializing in brooding, conflicted types, but he does have a lighter side.

“I’ve always done heavier roles; that tends to be what I’m cast in,” he says, adding that he’d jump at the chance to work with Paul Thomas Anderson. That said, “I’m not nearly as serious as a lot of the roles I play . . . . I would love to do comedy, just continue to do a variety of movies, to kind of switch things up.”

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Where you’ve seen him

Nick Stahl was only 12 when he was hand-selected to star opposite Mel Gibson in “The Man Without a Face.” Since then, he’s appeared on TV in HBO’s “Carnivale” and in movies such as “The Thin Red Line,” “In the Bedroom,” “Terminator 3: Rise of the Machines” and “Sin City.” More recently, Stahl portrayed a wheelchair-bound reporter opposite Vera Farmiga (“The Departed”) in “Quid Pro Quo,” which premiered at the Sundance Film Festival in January.