"I've dealt with situational depression. I do have an addictive personality. I can be self- destructive. I can be vindictive."

That confession could come straight from the lips of Mavis Gary, the caustic antiheroine of "Young Adult." Charlize Theron stars in the provocative comedy, which opens Friday in the Twin Cities. But screenwriter Diablo Cody didn't pen that stinging self-assessment as dialogue for Theron. It's Cody describing herself.

"Occasionally I think about experiences I've had or things I've lost, and I still feel bitterness about it," she said from New York City. "Definitely, I've related to Mavis at times of my life. But I hope I have a lot more lightness than Mavis does." No question about it. Cody, 33, is an irreverent, unfailingly candid wit, with a presence that outshines many a star.

Born Brook Busey in suburban Chicago, she graduated from college with a media-studies degree and spent four years in Minneapolis, working as an ad-agency typist and moonlighting as a part-time stripper and blogger.

A Hollywood talent agent encouraged her to turn her colorful posts into a memoir, 2006's "Candy Girl," and to take a swing at writing a movie.

Today she's an Oscar winner and one of Hollywood's few brand-name screenwriters. Steven Spielberg tapped her to create and executive-produce his Showtime cable series "The United States of Tara," which recently ended a three-year run.

Yet Cody insists that she shares a lot of Mavis' failings. The teen pregnancy comedy "Juno," which won 2008's best original screenplay Oscar, and "Jennifer's Body," a horror comedy about a destructive temptress, were fiction, yet in a way very personal, emotionally autobiographical stories, she said. Ditto "Young Adult," which reunites her with "Juno" director Jason Reitman.

If her new film is a self-portrait, it's one of the least flattering since Vincent van Gogh cut off his ear. Mavis is a divorced, self-absorbed, Minneapolis-based hack writer of semi-popular young adult novels. We see her passed out drunk on her messy bed, or trapped under the arm of a one-night stand. When Mavis learns her high-school beau Buddy (Patrick Wilson) and his wife are new parents, she revisits her "hick" hometown of Mercury, Minn., to wreck his happy marriage and reclaim him.

A new mom

If anything, Cody's personal life seems like a closer match to the happily married couple than to her cringe-worthy protagonist. She and her second husband, Daniel Maurio, welcomed son Marcello in July 2010. Cody's parents recently moved into a house just down the street from hers. She calls their move to Los Angeles one of the best things that's happened to her since the 2008 Academy Awards.

"It's so funny to see my dad, who's this lifelong Midwesterner, adapting to his new surroundings," she said. "He's already got a goatee."

She spent a long time imagining what pregnancy was like for "Juno," but it didn't prepare her for the reality, she said.

The biggest shock was emotional.

"For me the most surprising thing about motherhood is that I never, ever stop thinking about him. I notice I'm gnashing my teeth because I'm not with my son. Even when something else is in the front of my mind, like right now we're having this conversation, he is in the back of my mind always."

Even so, there's a constant press of work. Having her parents on hand to watch Marcello while she puts in her daily six hours writing at her office or a coffee shop has been a godsend, she said. "Help is an understatement. They're the backbone of the operation."

As grateful as she is for the breaks that have come her way, Cody says she sometimes feels as if she was sideswiped onto a superhighway she never intended to travel, and now she's obliged to stay on that path.

"Never once in my life did I utter the words, 'I want to be a screenwriter,' before the opportunity landed in my lap. Which is really, really unusual. I just decided to do the best that I could and take it as far as I could. And I guess I still ... I don't know what I'm doing."

Her long-term plans are a far cry from her recent world of flashbulbs and television interviews. "I would love to teach at a college someday. The run I had of being a public figure, that's not something I'm interested in at all anymore. I really am just interested in writing and being behind the camera and that's it."

As for future writing projects, "I want to write a young-adult novel. In fact, I've begun. There may be a paranormal aspect to it. I ain't dumb. I know what sells. There are no vampires, though."

A lack of social confidence contributed to what Cody considers her "biggest setback," the underperforming "United States of Tara."

"I feel like I could have come into that situation more educated and more prepared. I didn't because I was so used to flying by the seat of my pants and I have learned that you can't. That there are times in your life when you really have to buckle down, do your homework, do the work and be mature."

Momentum is key

"I have to keep working or I'll go crazy," Cody insists. "I just made a point of never dwelling on anything good or bad and just constantly maintaining forward momentum and just working, working, working."

What makes Diablo run, she said, is "fear. Because if I stop and think about things, it's like when the coyote in the Warner Bros. cartoon runs off the cliff. If you look down, you're gonna fall, so just keep going."

And so she has turned her Airstream vacation camper into a set for "Red Band Trailer," an Internet interview show. Each 15-minute webisode is a facetious celebrity interview; the current season features conversations with Jack Black, Zooey Deschanel, John Krasinski, Joel McHale, Amanda Seyfried and Sarah Silverman.

"We shoot it in the driveway of my house and it honestly started as a dare: 'Wouldn't it be funny if we made a talk show in the trailer? Let's call some friends that are famous and see if they'd be willing to be guests.' It just snowballed into a real thing, which was so funny. I know what a bad interviewer I am. I'm in on the joke, I hope our guests are in on the joke."

Even though she's met half of Hollywood, Cody says she's not completely blasé. The blood still leaves her brain when some celebrity she adores enters the room.

"I was on a plane today with Ryan Reynolds and I was like, 'I can't believe this.' I didn't talk to him, I just stared at him. I get very, very excited by celebrities. And by the way, they don't have to be big celebrities. I get very excited if I see somebody from a reality show."