Charlize Theron & Diablo Cody at the Cinema Society Screening of ‘Young Adult’

“In a lot of ways, I am not a mature citizen of the world,” Diablo Cody confessed at the Cinema Society & Dior Beauty screening of her new film, Young Adult, at the Tribeca Grand on Friday night. Directed by Jason Reitman, the flick follows teen fiction author Mavis Gary (Charlize Theron) as she makes her way back to Mercury, Minnesota to reclaim her high school sweetheart, Buddy Slade (Patrick Wilson), who has since married Beth (Elizabeth Reaser) and become a father.

Equal parts sentimental, washed-up, and sloshed-by-night, Mavis finds a friend in Matt Freehauf (Patton Oswalt), a nerdy guy whose locker was next to hers back in the day. Mavis’s homecoming is punctuated by the replaying of Teenage Fanclub’s ballad “The Concept,” her stash of scrunchies, and her attempts to bang out the final book in her series. She’s the motivating force behind one especially cringe-worthy scene at an afternoon party for Buddy’s baby, as well as a sort-of-sex scene that’s both fulfilling and startlingly sad. With the help of Matt’s sister, Mavis remembers that she’s better than the small town she once left behind, or at least tried to, and hightails it back to the big city the next day.

Though Cody would never pull such stunts herself, and said she never had a high school flame (“I liked a lot of guys,” she reminisced, “I was straight-up boy crazy”), she sees parts of herself in the character she created for Mavis. “I thought to myself, ‘I’ve been writing about teenagers for the last few years of my life… maybe there’s something wrong with me and I’m, like, a stunted person. So I started thinking, ‘Okay, I’d like to write about a woman who actually is unable to move past her adolescence and is acting out,’ and there it was.”

She didn’t draft Young Adult with Theron in mind. “I’m never that optimistic when I’m writing. I don’t ever assume that there’s going to be an actor involved at any point because the script could just wind up in the garbage. But Jason called me one day and said, ‘I think I want Charlize Theron to play this part,’ and I just thought, ‘Oh my God, we can only hope.’”

Reitman previously told the New York Times that he’d sent Theron DVDs of The Hills, Laguna Beach and My Super Sweet 16 ahead of filming. Theron says she counted on him to guide her through Mavis’s most inebriated moments. “Playing drunk is actually really hard. I find it really hard to do it in a way that feels believable,” Theron said. “I find watching it is hard and you can see right through it.”

Oswalt had nothing but praise for his co-star, saying, “I lucked out getting to work against her.” As for Cody, she added, “It’s cool to work with somebody that kind of gets all of your references and understands a lot of the pop culture shorthand that people use to communicate. You saw that in [Cody and Reitman’s] Juno, and this is such an amazing portrait of Gen X dragged kicking and screaming into 40.”

The evening ended at The Double Seven with a flurry of Grey Goose cocktails. Young Adult opens in limited theaters December 9 and nationwide December 16.

Photos: Patrick McMullan