‘The Rocker’s’ Teddy Geiger finds harmony

Hiding behind his floppy, jet-black hair, Teddy Geiger looks like any other kid making the uncomfortable transition between teenager and young adult. His shoulders hunched, his hands thrust deeply into his jeans pockets as he wanders through a throng of shoppers at the Grove on his way to a recent interview, Geiger doesn’t exhibit the swagger one might expect from an up-and-coming musician who also happens to be carving out a niche for himself in the world of acting.

In some ways, Geiger does resemble his character in the music-comedy “ The Rocker,” which opens in theaters today. The 19-year-old lends his soulful voice to Curtis, a talented but troubled teen who finds a father figure in his bandmate’s Uncle “Fish” (Rainn Wilson).

Although Wilson’s antics provide plenty of laughs, Geiger’s comfort in his role as the straight man gives the film a strong, sweet backbone.

“[Acting] started as, ‘It’ll help the music along.’ Just recently did I realize that I do enjoy it,” explains Geiger, who made his TV debut on the 2004 VH1 reality series “In Search of the Partridge Family” and went on to appear in the short-lived 2006 CBS series “Love Monkey.” “The more I do it, the more I like it, and the more I find the creative spaces in it.”

It was Geiger’s musical talent and introspective nature that made him right for the part, says producer Tom McNulty. “It’s one thing to be able to sing a song and play a guitar; it’s another thing to have charisma onstage,” McNulty says. “He’s got an old soul. He’s not this feckless teenager looking for success.”

Growing up in Rochester, N.Y., Geiger was encouraged by his parents to embrace his musical nature. His grandfather taught him to play the piano, and he learned the guitar, bass and drums. Once he graduated to writing lyrics and music as a preteen, his path seemed clear.

In 2006, he released a full-length debut on a major label, “Underage Thinking,” garnering an instant following with ‘tween girls and earning some solid reviews. (A follow-up, “TG33,” is tentatively due this year.)

Geiger spent much of his teenage years touring to support the album, but when he returned home, he found that the life he left behind had changed dramatically. “When I got off tour, my friends were all off in [college], and they weren’t around,” Geiger says. “I’m really close to the people I went on tour with, but they’re scattered all over the country.”

Still, being able to tap into his experience on the road didn’t make it any easier for Geiger to sing someone else’s material in “The Rocker.”

“It was a little weird,” Geiger says. “A lot of the melodies are melodies I wouldn’t necessarily sing; they’re counterintuitive to the way I would sing them. [But] I haven’t really done a lot of singing of other people’s material -- it helped me grow a little bit.”