It was a busy season for Denis Leary on Rescue Me. He incited an on-ice brawl, had sex with his dead cousin's widow, paid his godson to terrorize a man dating his estranged wife, and drank himself daffy while arguing with a ghost. ''I'm not a romantic comedy kind of guy,'' he deadpans. ''As a filmgoer, it doesn't interest me; as a writer, I can't write that stuff. But I can write f---ed-up guys. I don't know what that says about me.'' Well, it says here that Leary possesses enough intensity and combustibility to inhabit his role as an agitated antihero on the first-year FX firefighting drama. In Tommy Gavin, Leary, 47, has created a character that hits hard and close to home (he lost a firefighter cousin to a 1999 blaze and several friends on 9/11). ''I'm not gonna say it's easy.... It's connected so deeply to things in my life, but also with friends that I based it on.'' Doesn't Leary worry about upsetting his blaze-battling buddies who don't want the less flattering elements of their firehouses exposed? ''No, because I don't give a f---.'' And to think he says he's not a romantic comedy kind of guy.