Abe (Jordan Gelber), the unfortunate protagonist of Dark Horse, embodies all the worst traits of male-arrested development and none of the funny, adorable ones (Steve Carell would have never played this role). Abe is overweight, bratty and petulant. He’s well into his 30s, but he still lives at home with his parents and has no intention of moving out. His father (Christopher Walken) gives him a desk job at the family business, because he knows no one else would hire him. When he looks at his son, his eyes radiate disappointment.

Abe’s mother (Mia Farrow) plays backgammon with him and tries to be cheerful and supportive of his hobbies, which include collecting toy action figures. Abe drives an enormous yellow Humvee (he can afford it because he has no rent or expenses to pay) and when he meets a mopey young woman named Miranda (Selma Blair) at a wedding, he gets her phone number and starts treating her like his girlfriend, even though she’s so mired in depression she barely knows he exists.

Dark Horse is, in some ways, a horror remake of The 40-Year-Old Virgin: Abe seems to be beyond help, and he’s surrounded by facilitators who are doing nothing to snap him out of his funk. The only person who takes a genuine interest is Marie (Donna Murphy), a co-worker who may even be harboring a crush on him. But Abe treats her in a condescending manner, as if she were beneath him. In the films of writer-director Todd Solondz ( Happiness, Storytelling, Welcome to the Dollhouse), kindness is rarely rewarded, and even the lumpiest outcasts are capable of casual cruelty.

With Dark Horse, though, Solondz is up to something different. Instead of wallowing in nihilistic laughs and mocking Abe’s predicament, the filmmaker manages to make you care for this unlikable schlump, to see the vulnerability deep beneath his strident exterior. Gelber ( Boardwalk Empire) plays Abe as a righteously entitled whiner, the sort of petty man who strides into a store waving a receipt and demanding to see the manager over a $10 purchase. He’s exasperated by everything and everyone: He resents his brother (Justin Bartha) for being a successful doctor; he hates his father for squashing his dream of becoming a singer; and he demands his mom write him a check for the $800 she owes him, as if he were a bill collector.

In his earlier movies, Solondz would have made Abe pay for his crimes of ego and selfishness, or maybe even let him get away with everything, leaving a trail of broken people in his wake. In Dark Horse, Solondz takes a different route. There’s a genuine poignancy in the relationship between Abe and Miranda, who entertains the deluded man’s marriage proposal as a last-ditch effort to avoid suicide (he’s oblivious to her state of mind). There’s sweetness, too, in a funny scene in which Marie shocks Abe by revealing a secret side of her life, a reminder of how he’s making a mistake by always assuming the worst in people.

There’s a streak of compassion in Dark Horse, a sincere empathy for a thoroughly detestable man, that is as surprising as anything in Solondz’s earlier, more transgressive work. When Abe’s mother tells him, “We’ve written you off as a failure years ago; everyone knew,” she says it out of love, not anger, and you understand her intent. Dark Horse doesn’t end on an entirely cheerful note — Solondz will never be much for happy endings — but the film is strangely optimistic and at times borders on the whimsical. Who knew Solondz had this in him?