Relating to Chris Carmack -- The former ''O.C.'' star talks about his new role on The WB's ''Related''

As long as young-adult dramas need beefy, jerky heartbreakers, Chris Carmack will enjoy job security. After bedding Marissa and Julie Cooper on The O.C. and seducing an innocent on Lifetime’s Beach Girls, the 24-year-old is back as Alex, an NYU acting student who messes with Rose (Laura Breckenridge), the youngest Sorelli sister on The WB’s Related (Mondays, 9 p.m.). What’s it take to play the guy girls love to be destroyed by?

A badass catchphrase. ”In the airport once, a guy was on the phone and actually asked me to say ‘Welcome to the O.C., bitch’ to his daughter,” he says. ”I obliged. My first big TV line will live forever.”

The right hair. ”I auditioned with long hair, and [the producers] liked it,” he says of Alex’s very un-O.C. flowing locks. ”And I like it because with the short hair, I look so all-American and apple pie.”

Subtly varied forms of jerkdom (no matter what your mom thinks). ”I thought Alex was my opportunity to play a character who isn’t a straight-up jackass,” he says. ”But last week I was watching an episode with my mom, and she was like, ‘You’re such a jackass.’ I guess there’s nothing wrong with having a niche.”