Morissette's "You Oughta Know," on heavy rotation at radio stations all over the country, has become a cri de coeur for women -- and even some sensitive guys -- who revel in the tale of a girl who was sacked but is now giving the scumbag his due. "It was a slap in the face, how quickly I was replaced," she hisses over a slippery hip-hop beat and unruly, crunching guitars. "Are you thinking of me when you fuck her?" After her typically sold-out concerts, female fans come to Morissette, tears in their eyes, thanking her for fighting back through her songs. Music as empowerment, so to speak.

But a few years back, Morissette was far from the lusty, screaming banshee she is now. And any hint of anger and emotional venting over two-timing men ("Your House," the prerequisite unlisted track), parents' expectations ("Perfect") and religious identity ("Forgiven") was well under wraps -- and squeezed snugly into spandex.

In the early '90s, Morissette was Canada's queen of dance-pop. Known simply as Alanis, the squeaky-clean teen idol for thousands of pre-pubescent Canadian girls worked a Tiffany-meets-Taylor Dayne style, making slick, Janet Jackson-like videos in Los Angeles and releasing two albums. She even took home a Juno Award -- Canada's Grammy -- for most promising female artist.

Niceness? She oozed it. Heck, back in 1991 in her hometown of Ottawa, Morissette was singing gleefully into her headset while twirling around the stage with several buff, shirtless beefcakes in an opening slot for, of all people, Vanilla Ice. And while her growing legion of U.S. fans are unlikely to be aware of the old Morissette, her track record north of the border posed a dilemma for Warner Music Canada, the company responsible for selling the new, gritty Morissette to radio stations and jaded music journalists.

Considering the jarring contrast in Morissette's music, Warner was worried about a backlash. So some company employees hatched a scheme: they'd make the rounds of radio stations and newspapers with a tape of Jagged Little Pill, but they'd keep the identity of the performer secret. "One thought it was Tori Amos," says Mary Armstrong, a Warner regional sales manager. "I also got Bjsrk, National Velvet, Lisa Dal Bello and other guesses. They didn't know who it was until I gave them clues."

Norm Provencher, music critic for the Ottawa Citizen, concedes his jaw hit the table when Armstrong told him it was Morissette. For her part, Morissette says that if there are people back home who don't want to understand where her music is coming from these days, that's fair enough. If they think she's gone Hollywood or complain she's capitalizing on a trend, that's their problem.

For Morissette, the beginning of August was spent in Ottawa on a well-deserved break from relentless touring to attend the wedding of her brother Chad. Yes, she sang at the ceremony, but it's unlikely, judging from her laughing response, that "You Oughta Know" was the wedding theme. And though she loved being home, the singer was a bit peeved by certain Canadian industry types, who, it seemed, had written her off as just another nicely honed, angst-ridden-female singer-of-the-month.

"To tell you now that those things didn't hurt, well, I'd be lying," Morissette says. "But I've learned along the way that some people naturally have to be adversarial. You know, people who don't want to understand, just don't want to understand."

Morissette, only 21, has matured fast. And for most of her life, her raw talent has kept her ahead of the game -- though apparently, life was not always sweetness and light. Morissette and her twin brother Wade were born in 1974 to a French-Canadian father and a Hungarian-born mother. As a kid, she was boisterous, undeniably independent, with a flair for dancing and acting that eventually led to a recurring role on Nickelodeon's You Can't Do That On Television. The money Morissette earned from TV financed her first single, a homemade effort titled "Fate Stay with Me." By the time she was 14, Morissette had signed a songwriting deal with MCA Publishing in Toronto, and the crafting of "Morissette the Pop Star" had begun.

Trouble was, just as the bubbly, outwardly confident Morissette was climbing the pop charts in Canada, her personal life was coming undone. She left home in 1992 and moved to Toronto. By that time, her youthful exuberance and search for an identity had steered her into a handful of ill-fated romances, which left their share of scars. And when her second Canadian dance-pop album, Now Is the Time, didn't do as well as the first, the young singer had good reason to start questioning things. That, added to a particularly bad breakup, gave root to the "emotional purging" that would eventually end up on much of Jagged Little Pill.

Then one evening she spoke to an ex-boyfriend. "It bothered me that a whole year had gone by [since the relationship had ended] and I hadn't changed," she says. "I thought everything was fine, but it wasn't. Without holding back I wrote out all this stuff I felt -- about three pages worth -- for the sake of release." Morissette opted not to toss her angry diatribe into the trash, turning the scribblings into "You Oughta Know."

Morissette's break came after she moved to Los Angeles in 1994, where she continued writing through MCA and latched onto collaborator Glen Ballard, a producer/writer who had worked with Michael Jackson and Quincy Jones. The pair hunkered down in Ballard's studio and cranked out the 13 songs that would end up on the album.

The final piece of the puzzle came in the form of L.A.'s Maverick Records, the fledgling label set up by Madonna. Maverick took notice of the wide range of stuff on the Morissette/Ballard demos, didn't give a hoot about her sugary past and in no time offered her a contract.

The rest has been a shock to just about everyone involved. Nobody -- Morissette, Ballard, Maverick -- figured she'd get this big this fast. With its combination of primal-scream therapy, Morissette's vocal range and catchy, not-quite-bordering-on-cliche guitar-rock arrangements, Jagged Little Pill is arguably one of the more diverse debuts to come out of the current pack of alt-rock divas. And it's made quite a splash, with the CD going gold within two months of its release and "You Oughta Know" on the verge of saturation on MTV and radio.

"Look at it," says Abbey Konowitzh, Maverick's general manager. "Eight weeks ago, she was a complete unknown in this country. You're always surprised when any artist moves really quickly, but this kind of immediacy is rare."

More than that, her hit tune has even been used as a therapeutic tool. One night a few weeks back on Love Phones, the syndicated New York-based sex-talk show carried locally on KZFX/107.5 FM, resident sex therapist and psychologist Dr. Judy and host Jagger were listening to a female caller cry into the phone about a guy who had dumped her. Jagger hauled out "You Oughta Know," played a couple of verses and told the caller to get tough. "Now you go tell that guy to fuck off," he said.

But Morissette says she's not ready to be anyone's love doctor. "I guess I've always been somewhat of an advice giver, I mean I've always been the kind of person you could talk to until five in the morning," she says. "But as for me being given this whole new responsibility for other people's troubles, well, I don't agree with it. That's way too much pressure for one person. Just because someone writes music that people relate to doesn't mean they're a god, when they have enough problems being in charge of themselves, at best."

Another of Morissette's beefs, at least at the outset of her North American tour, was the moshing at her shows. "I mean, I didn't know what to do. I thought, 'What are these people doing, this record is not about moshing,'" she says. "But I get it now: if this is the way people want to get rid of their stress, then let them do it their way."

Don't expect Morissette to end up in the pit any time soon, though. That's one leap she's not prepared to take. Relationships -- at least in the immediate future -- are another. "With all these years that maybe I've been intellectually ahead of myself, well, I'll tell you, I have an emotional part of me that has to do some catching up," she says. "I still have things to learn."

For now, support from her parents is enough. "I can tell you exactly what my father told me over the phone when he called me up after he first heard the record," she says. "He said, 'So, Alanis, you're expressing some emotion. That's good.'"

Alanis Morissette performs at 8 p.m. Sunday, August 27 at Numbers, 300 Westheimer. Loud Lucy opens. The show is sold out. For info, call 526-6551.