This is the serious Emilio Estevez.

There is a less solemn version, apparently more common in California, who cruises clubs with buddies, picks up a blond now and again, and behaves not inappropriately for a 23-year-old.

That Estevez figured prominently in a New York magazine story that christened "The Brat Pack," a group of bankable and photogenic young actors with whom he has appeared in "The Breakfast Club" and now "St. Elmo's Fire" (which opens Friday). Estevez does belong to an informal sort of repertory company -- with people like Judd Nelson, Ally Sheedy and Rob Lowe -- but he doesn't like being branded a brat. What he calls himself is "a filmmaker."

"He neglected to mention that we are all hard-working young men and women," Estevez grumbles about his biographer. "This year I wrote three scripts. You don't get films made by going to parties.

"There will always be people laying for me," he philosophizes. "There's a lot of professional jealousy out there. They'll say I made it because of who my father is actor Martin Sheen and a million and one other excuses. If Hollywood gives you a break and it gives you stardom, then it can take it away. If you earn it, it can't take it away. I'm still not a star; I'm an actor. But what I've achieved, I've earned."

The serious Emilio Estevez, observe, is thoughtful, articulate, modest and so unwilling to pass through a door before a woman that one suspects parental admonitions about minding his manners still echo in his newly mown head. He may have launched himself in teen-type movies, may still look teen-aged in jeans and high-top sneakers, but he's planning to become one of those Hollywood hyphenates, a writer-director-star, a filmmaker.

Though the "St. Elmo's" cast is much in evidence at this chic midtown hotel -- there are Sheedy and Lowe, just back from "Donahue," there's Mare Winningham tucking her infant into a limo, here's costar and girlfriend Demi Moore kissing Estevez goodbye as he heads out for lunch -- Estevez hasn't come to party. He's going to talk, across a plate of tortellini, about things that matter.

Politics, for example: Estevez is a draft resister.

"A draft registration resister," he corrects. "My politics are sympathetic to the left, definitely. I was very politically aware, very culturally aware. Into Simon & Garfunkel at 6 years old, Bob Dylan, the Beatles. When Bobby Kennedy was shot I ran in to tell my father the news. I watched them pull the draft numbers out of the hat . . . The '60s and '70s didn't slip past me."

When he failed to register, he heard from the Selective Service.

"The letters were pleasant at first," he remembers. " 'Perhaps you may have neglected . . .' I rolled 'em up and threw 'em in the trash. The letters started getting shorter and nastier. 'Five years and/or $10,000.' I had avoided it for four years, made contributions to the Committee for Conscientious Objectors, passed leaflets out in front of the post office. Finally I said, 'I must do this.' Four years of passive resistance was statement enough. When I finally signed the card, I wrote on it, 'I am signing this under duress.' "

It is language out of another era, uncommon among his peers.

"Sometimes it's frustrating," Estevez acknowledges. "You talk about a certain event and it's Greek to them."

Estevez, on the other hand, is paying attention.

"I watched the news last night. What'd he give them [the Nicaraguan contras]?" he asks, "$17 million? $22 million? The people in Nicaragua seem pretty happy with the way their country's being run. If our government says, 'No, they're not,' and sends troops there, that's something I won't participate in."

He may not have to. Though properly registered, Estevez has been compiling a file he hopes will justify CO status if the draft is reinstated: an antiwar play he wrote while still a Santa Monica High School student, letters from teachers, and his role in "Mister Bomb," a short film certain California theaters have banned for vulgarity. ("I play a quadriplegic who doesn't get into the shelter in time and gets cured by the radiation," he explains.) The alternative -- going to jail for failure to register -- had little appeal. "I would have had to give up a lot," he says.

Indeed. Estevez is living just the sort of life he envisioned for himself when he began auditioning for parts at age 16. He's been working steadily since the day he simultaneously graduated from high school and won his first part in a television movie. He had a small part in "Tex," played Two-Bit Matthews in the film of another S.E. Hinton novel, "The Outsiders," appeared with his father in a television movie about young criminals ("I was cast before he was") and starred in art houses and on videocassettes everywhere as the intense punk in "Repo Man." He never really considered doing anything else; in fact, he skipped college.

"I had pretty much had it with organized education," he says. "I spent a lot of my life traveling and I knew that's where I got most of my education, not in school. I was very fortunate to have that advantage," he adds, not wanting to appear overprivileged, but not regretting the lack of diploma, either. "I see my friends who went to college doing the same things I did when I was 16. I'm not belittling them" -- the serious Emilio Estevez doesn't want to sound boastful or anti-intellectual -- "but if I'd gone to college I'd just be making the rounds."

No one actually taught him to act or to write, he just acted (in home movies with neighbors like Sean Penn and Rob Lowe) and wrote. Still in grade school, he submitted a script -- in pencil, on lined paper -- to "Night Gallery."

"Nobody really taught Mozart how to compose at 5, or any of the world's great artists," he points out, momentarily relinquishing humility. His solemnity also wavers once or twice: Estevez says he insists on having "a lot of laughs" in everything he does, which is not exactly Woody Allen's perspective. But seriousness wins out.

Instead of making the rounds, Estevez is on the verge of producing and directing. As he speaks, the major studios are getting a look at "That Was Then, This Is Now," a film of still another S.E. Hinton novel. It was shot last summer in Minnesota, Estevez starring as an sociopath with an earring in the screenplay he wrote after he optioned the novel (he was 19 at the time) and helped find backers. Now all it needs is a distributor.

"Those books have sold millions and millions of copies and from a studio's point of view, we should have millions of viewers. Unfortunately, I don't think the translations from book to film have done Hinton justice," Estevez says seriously. " 'Tex' came the closest. 'The Outsiders' was a 14-year-old's nightmare. 'Rumble Fish' was technically brilliant. We've been able to learn from the other pictures. We made it very contemporary, hired a brilliant cinematographer. The cast is primarily unknowns so it has a real feel -- you're not watching movie stars. The emotional content is so rich, so full, it's absolutely draining. It's a terrific movie."

Meanwhile, Estevez is finishing the rewrite of "Clear Intent," a script "I'll probably end up directing, which is very exciting. It's about two garbagemen in Los Angeles who get involved in a murder and whose lives change overnight. A black comedy, like 'Repo Man,' only more realistic." John Hughes (director of "Sixteen Candles" and "The Breakfast Club" ) will be its producer and "godfather -- he's been an incredible influence, an inspiration, the way he writes, his humanity."

And there are two other scripts Estevez can't talk about much. One came rocketing out of his Compaq "in six days. 98 pages. No sleeping, no eating, no bathing. No plot, not knowing where the hell the characters were going, just knowing how they'd react in a certain situation," he says.One is for himself and Demi Moore, who plays a voguish coke head and banker in "St. Elmo's." "We've known each other for a long time," Estevez says, looking pained at the intimation of womanizing in the Brat Pack story.

All right, might as well get into the sore subjects. Like his name -- why is Martin Sheen's son using the surname Sheen jettisoned for the stage? Two other actor brothers have split on the surname issue: one's Charlie Sheen, one's Ramon Estevez (the surname Martin Sheen was born with). And why won't Emilio do interviews with his father and brothers? Doesn't he like the idea of another acting dynasty, like the Carradines or the Bridges?

"No, not at all. That's why I won't use the family name. All the way through high school it was always Estevez," he says, pronouncing it Es-TEH-vez. "It's not a sore subject. I'm here to talk about my accomplishments and career and to sell a picture and to talk about my family. And my father is not why I came. If the press wants to know what he thinks, then ask him. I love him and we get along great but we're separate people with two completely separate careers. I never rode his coattails."

And what about the Brat Pack?

"Very discouraging, but you have to laugh it off," says Estevez, who isn't laughing; he's afraid the label will follow him forever. "What I learned is the press is never really your friend. If I were in the hospital, that reporter wouldn't be by my bed. Now I'm a lot more guarded. I came to New York with a bulletproof vest on."

The same question arises later in the day on the David Letterman show, of which Estevez is "a big fan." He gets far less time than the far less interesting Susan Saint James but grins when Letterman confesses that "Repo Man" is "the only film I've ever rented."

Estevez insists, again, that this alleged Pack is "kind of a fabrication." The less serious Estevez makes a brief, unannounced appearance, however. Perhaps it is not entirely out of character that he had earlier entertained the notion of a lunch-hour interview at the Hard Rock Cafe before realizing, with some regret, that the decibel level there was not conducive to serious talk about filmmaking.

"We just have a good time being . . . guys," Estevez explains.

"Say I get to join -- what can I look forward to?" Letterman says of the Pack, sounding more middle-aged than usual.

"Late nights at the Hard Rock Cafe," says Estevez, with relish. "Clinking beer bottles. Having a good time."