Much ado has been made of the brutal, minefield-esque sisterly relationship between Nicole Kidman and Jennifer Jason Leigh in Noah Baumbach's "Margot at the Wedding," out Nov. 16. Equally central to the film's devastating portrayal of familial dysfunction is the pas de deux between Kidman's Margot and her son, Claude, played by Zane Pais. A New York native and son of two thespians, Lisa Emery and Josh Pais, the young Pais, 14, makes his acting debut as the preadolescent Claude, a sweet-natured boy who accompanies Margot to the wedding of her estranged sister and sometime best friend, Pauline. Through Claude's eyes, we watch as Margot launches critical barbs on all who approach her. "I think he really wants to be her friend," explains Pais of his character. "And she's kind of pushing him away. She's pushing everyone away during the whole movie. That's disturbing that someone would push away the people that they love the most."

OPEN CALL: Pais' casting process was a bit more rarefied than most. His mom was starring in the play "Abigail's Party" with Leigh and the then-12-year-old Pais was doing his homework backstage when, on a lark, Leigh thought of him for Claude. "She was talking about the movie, which was yet to be titled, and she said maybe we could read it, just me and her backstage," recalls Pais. "So right after the play was done we just kind of sat in the green room and talked and read lines." Pais later auditioned at Leigh and Baumbach's apartment (the two are married), and a month later, he had the part. "When I found out, I was just coming home from school and my mom just told me, 'Congratulations.' At first I thought she was playing a really mean joke on me."

HIT ME BABY ONE MORE TIME: With no acting experience under his belt, Pais soon found out that none other than Kidman would be his mom. Though the intimate rehearsals and Kidman's kindness helped quell his nerves, the shoot in Hampton Bays, N.Y., wasn't all smooth sailing. One particularly rough scene has Claude being beat up by neighborhood kids and then receiving a slap in the face from Margot, instead of sympathy. "I had to be slapped over and over and over again. They couldn't really fake it," he says. "I was actually getting slapped by Nicole Kidman....By the time we were halfway through the scene, I was getting really upset."