While sports movies are commonplace, the sports-fan movie is a comparative rarity.

Those we do see ("The Fan" or "Celtic Pride" or "Green Street Hooligans") suggest that there is something pathetic or pathological about grown men who make outsized emotional investment in a professional sports franchise. (As do those awful ads for "Monday Night Football," wherein hapless losers are redeemed by a televised game.)

Exceptions include "Fever Pitch" and its comic portrait of a Boston man who sees his love of the Red Sox as a spiritual thing - evidence that he believed in something larger than himself.

That turned out to be BS that he's slinging to his neglected girlfriend, but it's funny BS, and leads to a more mature integration of his two loves ("Pitch" is an underrated movie from a Nick Hornby soccer-fan memoir Americanized by the Farrelly brothers).

The peculiar indie "Big Fan" has a darker view, and seems to start out on the road to condescension. It examines the life of "Paul from Staten Island," a rabid Giants fan who lives for football games and for the two minutes he spends each week defending the Giants on his favorite sports talk show, answering the taunts of an Eagles fan named Philadelphia Phil (Michael Rapaport).

Middle-aged Paul has one friend (another Giants fan), no romantic life, still lives at home and spends his free time composing talk-radio rants with pen and paper, one of two main uses he makes of his right hand.

So, he's a socially maladroit loner who still lives with his mom. Paul's the kind of fellow who shapes up as a figure of ridicule, and there is some of that in "Fan." The plot, for instance, gets rolling when Paul follows a Giants star player to a strip club, his admiring gaze is fixed on the linebacker while buxom strippers dangle their wares in front of his heedless eyes.

When Paul screws up the courage to introduce himself (to the player, not the women), the meeting goes horribly awry.

To say that reality delivers a cold slap in the face is putting it mildly. He's forced to question his devotion to the team and the way he's built his entire life around the rituals of rooting.

Paul's response to that soul-searching is complex. Writer-director Robert Siegel (he wrote "The Wrestler") is obviously interested in obsessive types and finds something to defend in the passion that his characters bring to their single-minded pursuits.

That's a tall order in the case of Paul, whose own family seeks to declare him mentally incompetent. And maybe he is. But in his own way, Paul is content, and comfortably sure of his place in the world.

Siegel tries to find some nobility in that, imbuing "Big Fan" with a surprising amount of humanity, and something many movies don't have - an ending.

Paul eventually decides that his real problem isn't football fanaticism at all. It's Philadelphia Phil. In the closing moments, he heads to a Passyunk Avenue sports bar for a gameday showdown with his talk-show nemesis.

The offbeat "Big Fan" stays poised on the edge of comedy and tragedy, and doesn't tip its hand until, well, the final gun.