HER `CRUEL INTENTIONS'; MOVIE SHOWS ANOTHER SIDE OF SARAH MICHELLE GELLAR.

Byline: Bob Strauss Daily News Film Wrr

As TV's ``Buffy the Vampire Slayer,'' Sarah Michelle Gellar has become the idol of millions by vanquishing evil while coping with teen-age insecurity.

In her new movie, ``Cruel Intentions,'' Gellar could shock her loyal following by embodying evil that ruthlessly exploits teen-age insecurity.

An update of the 18th-century French novel ``Les Liaisons Dangereuses'' set among modern, ultra-wealthy Manhattan teens, the movie features TV's blond, buff Buffy as a dark-haired, heartless manipulator who revels in vicious sexual gamesmanship.

``Well, I really am a brunette,'' the energetic 21-year-old chirps. ``I think the fans will think it's a departure. It's important that everyone remembers Buffy is a character I play, as this girl Kathryn is a character I play. None of them are really me. I hope everybody realizes that I am an actress and that I can do other things.''

Absurd as it sounds, Gellar's portrayal of the karate-chopping, stake-wielding demon fighter has left er with a good-girl reputation that's hard to shake. Even ``Intentions'' director Roger Kumble had to be convinced that she could handle the relentlessly nasty Kathryn.

``When I initially talked to Sarah about the role, I asked `Are you comfortable doing this? You're an icon on television,' '' Kumble recalls. ``She was like, `I'm an actor first. I'm really drawn to this material, and I want to play this role.' ''

Kumble was hesitant despite evidence that Gellar could act very bad indeed. Before ``Buffy,'' she played the chip-off-the-block daughter of Susan Lucci's villainous Erica Kane on the daytime soap opera ``All My Children'' - and won an Emmy for it.

But that teen-age terror was just a kid compared to ``Cruel's'' Kathryn.

``When I left the soap, I figured that, for the rest of my life, I was going to be fighting the stereotype of the bad girl, the evil vixen,'' Gellar reveals. ``And I was very young, which is a weird time to feel that, which I did for a while. But then, all osudden, I was Buffy, and I had to prove that I could do this character that I figured I would be tagged as forever.

``It was a strange turnaround, and it did take a little convincing. It was still a change, too, because I don't think I was as aware of my sexuality on `All My Children.' I was still a little more awkward at that time; being 16 and trying to seduce Michael Nader was not the greatest thing for me.'' Some aspects of ``Cruel'' were a little more comfortable. For one thing, Kathryn's partner in serial seduction, her stepbrother Sebastian Valmont, was played by a trusted friend: Ryan Phillippe, with whom she co-starred in the hit horror thriller ``I Know What You Did Last Summer.''

``It made it easier to have a pre-established comfort level with the person,'' says Phillippe, who exchanges both highly provocative dialogue and teasing, intimate caresses with Gellar throughout the movie. ``Sarah and I have developed, over the years, a kind of antagonistic brother-sister repartee, and that itself to this movie particularly well.

``And it certainly made the more physical bits less awkward,'' adds Phillippe, who in real life is romantically involved with Reese Witherspoon, ``Cruel's'' other leading lady. ``It's much easier to do that with someone you know well enough to understand that there's not some imaginary line you're going to cross with them, that they're going to smack you or something.''

It also helped that the film required no female nudity and that Gellar had no sex scenes. Nevertheless, the young trouper, who's been working professionally for 15 years, did have difficulty with one bit: her first kiss with another woman.

``Leading up to it, I kept thinking, what's the big deal?'' Gellar reports. ``I kiss David Boreanaz (who plays Buffy's undead boyfriend Angel on TV) all the time, and we're not intimately involved. It shouldn't, technically, be any different; it's just another actor in another scene.''

But when it came time to film the smooch with actress S Blair (Zoe of `Buffy's'' WB sister show ``Zoe, Duncan, Jack & Jane''), Gellar had a panic attack. And understandably so; the scene took place on a warm spring day in New York's Central Park, with hundreds of onlookers and dozens of paparazzi scrutinizing every lip twitch.

``I'm thinking, these pictures are going to wind up in a tabloid somewhere with captions that make it look like they caught me doing something,'' she recalls. ``All these things were going through my head.''

``Cruel Intentions'' has the potential for putting a lot of things in its target audience of impressionable young people's heads. It is, after all, taken from the same story that inspired the decidedly adult ``Liaisons Dangereuses'' stage hit and its two R-rated movie interpretations, ``Dangerous Liaisons'' and ``Valmont,'' a decade ago.

Though ``Cruel'' boasts an R rating, too, Gellar's participation all but guarantees her younger teen fans will want to see it.

``I think it's great if you want to take youryear-old to this movie, then discuss it afterward and make sure they understand that this is not OK, this is not acceptable behavior,'' Gellar says, as if adolescents are really going to attend the movie with their parents. ``I'm glad that it does have an R rating. If it went for a PG-13, the movie wouldn't have worked as well. And, unfortunately, in public high schools these days there are a lot worse things being discussed - and happening - than what goes on in this movie.''

True. But parents still worry. Maybe they can take some comfort in the fact that Gellar might not be the movie magnet her ``Buffy'' popularity would indicate. A month ago ``Simply Irresistible,'' a lame romantic comedy/fantasy that was her first attempt at headlining a feature, bombed at the box office.

``I think we did some pretty nice work in it but, unfortunately, it didn't turn out to be the movie we set out to make,'' Gellar says of ``Simply.'' ``It was hard for me, but I learned a lesson early and, hopefully, it didno me too much damage.''

If a recent visit to San Diego was any indication, Gellar's popularity hasn't waned in the least. And she's learning how to deal with fame, too.

``I went to a movie with some friends, and when we got out, 50 people were waiting for us, and they followed us back to the hotel, and it was getting dangerous,'' she says. ``A year ago, I would've been crying, I would've been freaking out. But I knew how to deal with it this time, and so did my friends.''

Of course, stardom has its upside.

``If you learn how to take advantage of the perks, it's incredible,'' she acknowledges. ``We also went to Sea World, where they named three new baby otters Buffy, Willow and Xander (after characters in the show). They gave us a backstage tour of Sea World - we got to go into the penguin habitat and play with the penguins, which you're never allowed to do, feed a whale, play with the dolphins - it was this totally unbelievable day. Stuff like that is fabulous.''

As for the e-or-less) human Buffy, Xander, Angel and company, their show is heading in some seriously new directions. Boreanaz and another co-star, Charisma Carpenter, will leave at the end of the current season to work on a spinoff series. And Buffy herself will graduate from her high school that sits atop a portal to hell in order to attend another disquieting institution in the fall, college.

What'll be the deal there? Wormhole into a demon dimension?

``I think the writers are afraid we'll talk about it too much, so they haven't really told us what's going to go on next year,'' she says.

Whatever it is, Gellar should be able to handle it. She claims that stability is a major virtue as far as she's concerned. And ever since she first started doing commercials as a little girl in New York City, Gellar has certainly displayed a maturity well beyond her years.

Ask what her big passion in life is, and she'll tell you collecting rare books. Whatever dating she does do is kept strictly out of thdia spotlight.

Gellar humbly suggests that her hard-working, self-controlled demeanor may just be a characteristic of her generation of actors - although that would make them the only show-biz group in human history ever known for its premature maturity.

``We're not raucous, we're not wild, we don't go out and party till 2 in the morning,'' she notes. ``You haven't heard one story about this new group of actors I run with beating up photographers or trashing a hotel room. We're a very sedate bunch. We're a group that's about the job, about creating and entertaining.

``I wish I could pinpoint why,'' she muses. ``Maybe Hollywood is just being pickier now. Maybe they're keeping this on the ones that can handle it, the ones that can be successful and not let it crack them.''

Even if they can pretend to be good at being very, very bad - something Gellar says she learned how to mimic from hard experience with experts.

``I think everybody knows a Kathryn,'' Gellar says. ``I know sel, specifically. I went to school on the Upper East Side of Manhattan with privileged girls that had a lot of wealth very early and that had very little parental supervision.

``Now, everyone may not know someone with Kathryn's kind of power and wealth. But we all knew the bitch of the school, the one that controls everything. High school is that hierarchy, and if you're not in the most popular group, it is a miserable experience, let's be honest. Anyone who says that they enjoyed high school is either lying, or they were one of the most popular people, I always say.''

And Hollywood popularity is, of course, sweeter anyway. As sweet, in fact, as vengeance.

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2 Photos

Photo: (1--Cover--Color) Bad as she wants to be

Sarah Michelle Gellar has `Cruel Intentions'

(2) no caption (Sarah Michelle Gellar)