Prepare for family fireworks on NBC's hit "Law & Order: SVU."

On the Tuesday episode, "Philadelphia," detective Olivia Benson (Mariska Hargitay), who was conceived when her mother was raped, discovers she has a half-brother. He leads her to the father she has never met.

Michael Weston, who terrorized Michael C. Hall's character in HBO's "Six Feet Under, will do two episodes as Benson's bro, Simon Marsden. The second, "Florida," will air during May sweeps.

"After eight seasons of searching, we thought it was time for Olivia to have someone to hold onto," says "SVU executive producer Neal Baer. "She's been looking all her life for answers to the fact" of her birth.

"She's always wanted to know if there's anybody out there she's related to, as painful as that information might be. She comes to understand her past. ... When she finds her father, she finally has closure."

Baer was in Philly the other day to speak at a luncheon sponsored by the University of Pennsylvania's critical-writing program. (Full disclosure: This reporter teaches in the program.)

Benson's sib surfaces during a DNA "kinship analysis" performed in a rape case she's investigating outside her jurisdiction. She gets a hard time from Kim Delaney ("NYPD Blue"), playing a local precinct captain.

Benson tracks down Marsden in prison. "It's an issue of 'Like father, like son,' " Baer says.

"SVU" runs in Weston's family — his father, John Rubinstein, played a judge in an episode in '05. Weston's grandfather was legendary piano virtuoso Arthur Rubinstein.

Unlike "Law & Order" and "L&O: Criminal Intent," "SVU" routinely delves into the private lives of Hargitay's detective Benson and her volatile partner, Elliot Stabler (Chris Meloni), among others.

In Dick Wolf's criminal justice system, however, not all creative elements are equally important. He doesn't like personal stories, and he doesn't like stars.

Given that Hargitay and Meloni just re-signed for an un-Wolfish $6.5 million each, how did Baer defang the Wolf on both counts?

"What works for 'Law & Order' may not necessarily work for 'SVU,' " says Baer, 50, a Harvard Medical School grad and pediatrician. He was a producer for "ER" for seven seasons before joining "SVU."

For starters, "SVU" is the most popular of the "L&O" franchise and is NBC's No. 2 show, Baer says. Also, Hargitay's winning an Emmy for best actress in a drama last year didn't hurt.

"I guess I could write a strictly procedural show, but I'm so interested in characters," he says. "I like to know what makes them tick."

To Baer, Benson "represents the empathy and compassion we all feel for the victims." Stabler: "the rage." Hargitay is the real star, Baer says. They've been friends since she played Anthony Edwards' girlfriend on "ER."

Adam Beach ("Flags of Our Fathers") will join "SVU" next season as new partner to Ice-T's detective Tutuola. Richard Belzer's John Munch will stick around, Baer says.

P.S.: Baer has exactly one TV in his home, which he keeps in a locked guest room so his 16-year-old son can't watch it during the week. It was a gift from Wolf, he says.