The filmography of Joel and Ethan Coen brims with central characters to whom terrible things happen that they don't deserve. Llewyn Davis is not one of those characters. He's an unrepentant jerk, a couch surfer expecting invitations to crash, and a surly houseguest then.Llewyn (pronounced Loo-enn) is also a gifted folk musician, with a way of expressing the emotional essence of songs composed by others, in different times and places. Every time he sings, his voice suggests that beneath his churlish disposition Llewyn might be more empathetic, or simply nicer, than anyone has had a chance to know.Crafted by the Coens with their signature random deadpan style, Inside Llewyn Davis begins and ends with the title character punched in the nose. By the second assault we understand why; it's just another coda in the antisocial life of a charismatic artist. The Coens fashion an atmospheric descent for Llewyn, a meticulous re-creation of Greenwich Village's folk scene in 1961, around the time Bob Dylan hit town.Inside Llewyn Davis opens intimately with Llewyn, a role inhabited in body and voice by Oscar Isaac, performing on the Gaslight Cafe stage. Music is more vital than ever in the Coens' storytelling, with frequent collaborator T-Bone Burnett coordinating an expressive folk music sampler, and actors performing songs as character shading. Isaac's opener, the plaintive traditional Hang Me … Oh Hang Me, reveals as much of his restless spirit as his talent.The Coens and cinematographer Bruno Delbonnel track that spirit through episodes of Llewyn's insensitivity, a lodging parasite moving from host to host. One stop is Jean (Carey Mulligan), a former singing partner whose glare when he shows up sums up their relationship. Except for one night when they got drunk, had sex and now she's pregnant. Her live-in boyfriend Jim (Justin Timberlake) can't know. That won't stop Llewyn from asking him to borrow money for someone's abortion.An easier touch is an academic couple (Ethan Phillips, Robin Bartlett) impressing friends by having a starving artist hanging around. One morning Llewyn awakens and accidentally gets locked out with their tabby cat, forcing him to act responsibly for mooching's sake. The cat joins him on a path of least resistance leading to a road trip to Chicago in the company of a sickly Tennessee Williams caricature (John Goodman in full bluster). Meanwhile, folk music is becoming novelty songs and sweater acts Llewyn won't do.With all the problems Llewyn creates for himself, it's telling that he doesn't write songs about them. Creatively, he bums off the past just as he begs in the present, singing other people's songs. Dylan's doing something different, and Llewyn is on the edge of obsolete without a clue. A hard rain is gonna fall, and it couldn't happen to a more deserving guy.Steve Persall can be reached at [email protected] or (727) 893-8365. Follow @StevePersall on Twitter.