Director Jason Reitman and screenwriter Diablo Cody reunite their talents for Young Adult, a sometimes unsettling black comedy with a tender side that connects because of funny, sympathetic performances by Charlize Theron and Patton Oswalt.

Reitman and Cody, who previously worked together on Juno, once again find artistic synergy, as the former's sensitivity complements and gives depth to the latter's darker instincts.

Their subject this time is Theron's Mavis Gary, a teen fiction author who lives in Minneapolis. From the outset, Reitman and Cody illustrate Mavis's miserable existence — we see her chugging straight from a 2-liter of Diet Coke, half-watching Keeping up With the Kardashians and waking up with a stranger in her bed, on whom she casts an uncomfortable gaze as he sleeps. When she's not in her featureless, dorm-like apartment, she's in public places with her laptop, eavesdropping on teens for dialogue.

Mavis writes well for shallow teenagers because she thinks like one of them (albeit a highly intelligent one) — focused only on her own gratification, assuming that the world exists for her benefit and rationalizing its indifference to her. Frustrated that she doesn't have the life she thinks is owed her, Mavis packs a bag, scoops up her nervous dog, and sets off in a Mini Cooper for her hometown of Mercury, Minn., where she plans on reconnecting with old flame Buddy Slade (Patrick Wilson).

The kink in that plan: Buddy is a wholesome, All-American guy with a wife he adores and a new baby.

Mavis knows his situation, but it isn't stopping her. After meeting Buddy's wife and baby, her resolve only deepens, convinced that she and her former lover are meant to be together, and projecting that Buddy is unhappy with his circumstances. Her obsession is reflected and nurtured in her novel, whose heroine shares her plight: Her dreamy object of affection hasn't yet realized they are meant to be together.

Trying to talk some sense into Mavis is Matt (Oswalt), one of the uncool people Mavis the prom queen ignored in high school. Matt has some pretty big problems of his own, mostly stemming from the emotional and physical scars suffered as the victim of a hate crime. As Mavis's plans to seduce Buddy hit one stumbling block after another, she finds refuge in Matt's company and especially in his garage filled with homemade whiskey.

Oswalt, perhaps best known as a comedian, adds an acerbic edge that suits his damaged character and gives voice to our own disapproval of Mavis's actions. He's honest and brave enough to tell her "guys like me are born loving women like you."

We believe in Matt's attraction to Mavis because Theron brings out the humanity in a character who is otherwise some seriously damaged goods.Reitman allows us to sympathize with her by focusing on her alienation from her surroundings and from herself.

Soon after arriving in town, her face registers depression and condescension as she looks over the big-box stores and fast-food chains that line the road. Mavis honestly feels that she's better than her hometown and its residents, and harbors a mixture of pity and disgust for them. Though her critique is not without some merit, the irony is that her Mercury acquaintances feel the same way toward her.

Theron is both sympathetic and loathsome in a performance that should put her in contention for the season's best actress awards. She's both beauty and the beast, teetering on the edge of growth and regression.

Even when she's being a monster, you can't take your eyes off of her.