You can't read James Frey's memoir "My Friend Leonard" without thinking, this guy Leonard is unbelievable. He's a Las Vegas mobster, a high-level bookie, a bon vivant who can charm young hipsters and stodgy parents, a loving friend who's always there when you need a savvy sounding board, and an expert on just about any kind of visual art you care to mention. And he always picks up the check. But if you plan on confronting Frey with the idea that the main character in the follow-up to his best-selling debut, "A Million Little Pieces," sounds more like fiction than fact, know this: Frey's ready for you. "People always said, 'This guy's too good to be true,' when they met Leonard. And he was," Frey says in an interview in a coffee shop near his apartment in lower Manhattan. "But that's the thing about the people you meet in rehab. Normal, sane, healthy people don't wind up there. Knowing him was completely ridiculous and surreal."

A crack addict and an alcoholic by the time he was a teenager, Frey landed in a rehabilitation clinic at 23, an experience he described with painful vividness in "A Million Little Pieces." In rehab he met Leonard, who was trying to kick a cocaine habit. When both men got out, Leonard more or less adopted Frey, who was determined to turn himself into a writer. While Frey was busy failing at screenplays, Leonard gave him jobs to do--until the day a senile mobster in his bathrobe chased Frey off with a pistol. Frey approached writing with the same determination that allowed him to face two root canals without anesthetic in "A Million Little Pieces." Leonard was just as determined to wear down Frey's resistance to vulnerability and affection. Wherever Frey was living, Leonard would pop in from Las Vegas and not only take him out to eat but take all his friends as well. Leonard once called to say he was coming for a visit and could he bring anything. "Can you bring me a showgirl who'll make all my troubles go away?" Frey joked. "I actually can," Leonard told him. Who wouldn't want a friend like that?

As smart as it is heartfelt, this tribute to friendship is a far sunnier book than Frey's debut. Still, it has its share of darkness, beginning with his girlfriend's suicide and ending with an AIDS-related death. Bracketed by tragedy, the positive stories in the middle look a lot more fragile, and a lot more precious. And Frey's cool, shrewd eye for detail ties it all together, whether he's describing the inside of a jail, a Super Bowl party or the plaintive rootlessness of life in Los Angeles, where there is always a "feeling that people are... waiting to move somewhere better, that the dream is almost fulfilled."

Frey, now 35, with a wife and a baby girl, has been done with drugs and alcohol for 12 years. Now he's done with memoir. "I don't want to be a guy who writes books about himself for the rest of his life. Everything from here on will be fiction." And he has no doubts that he'll keep writing. "I hear writers talk about how they hate the writing, hate going to the desk," he says in the coffee shop. "There aren't many things that make me happier." Then, in a move that would make Leonard beam, Frey fights for the check.