THEATER : IDOL TEARS : For years, no one would take David Cassidy seriously. But finally, that’s changing.

“Some people call me a teen - age idol, but that’s not really me,

I guess they’ve got no way of knowing how lonesome I can be.”

*

Those words were sung in the 1950s by Ricky Nelson, the first television-spawned teen idol, and they have applied ever since. For all the easy fortune of cathode tube Adonises, their stardom always seems to be bittersweet and short-lived, with a stigma that lingers.

“It seemed whenever I’d read my name, it would be David ‘former teen idol sex symbol’ Cassidy,” says former teen idol sex symbol David Cassidy. “I used to think, ‘Well, I guess I’m going to have to do something more significant in my life, like David ‘convicted felon’ Cassidy or something,’ anything that would erase that convenient label.”

Fortunately, the onetime Partridge Family heartthrob hasn’t had to resort to a life of crime. Rather, he has been rescued by the Willy Russell musical “Blood Brothers,” in which Cassidy appeared for 10 months on Broadway. He reprises his role at the Orange County Performing Arts Center beginning Tuesday.

In “Blood Brothers,” which Cassidy describes as more a play with music than a traditional musical, Petula Clark plays a working-class mother of twins. Unable to care for the children she already has, she gives one twin (played on Broadway by Cassidy’s half-brother Shaun; played here by Tif Luckenbill) away to a wealthy woman, while the other, Mickey--played by Cassidy--grows up in poverty. Unaware of their relationship, the fraternal twins later meet and become friends until they fall in love with the same girl.

If “Blood Brothers” has rescued Cassidy from his teen-idol label, it’s only fair, since it was his and Clark’s addition to the Broadway cast that saved the production from a perilously low box office. When they joined in August, 1993, the show had been losing $32,000 a week. With their names on the marquee, it quickly began turning a profit, getting raves from audiences and even faring well with critics.

The acclaim Cassidy has received in his role has led, he said, to other Broadway offers and a promising TV pilot. And finally, at age 43, he says he is back on the path of serious acting that he was sidetracked from a quarter-century ago.

Cassidy spoke by phone from a hotel in Denver, where he was registered under an assumed name because, he said, some things never change. There are still fans who try to track him down. He considers the precautions he has to take to maintain a private life part of the deal that comes with success.

“I don’t see it as a bad thing, just part of my life. I suppose there was a time for me when the assumed name wasn’t necessary. I guess it’s good news that it is again, isn’t it?” he said with a laugh.

Cassidy’s mercurial success story is related in his autobiography published last year, “C’mon Get Happy . . . Fear and Loathing on the Partridge Family Bus.” A Cliffs Notes brief on the book might read:

All David Cassidy--son of actors Jack Cassidy and Evelyn Ward, stepson of Shirley Jones--wanted was to be a serious actor and play guitar like Jimi Hendrix. Instead, he signed on with a huge promotional machine that put his face on TV, magazine covers and lunch boxes and had him record simplistic pop tunes. Sure, he partook of the fruits of that: the millions in concert earnings, the pampering by toadies, the blind adulation of 50,000 screaming fans a night, the moist assignations with oodles of willing young fans and groupies. But do you think for one minute that made him happy? Nope. Afterward, no one took him seriously, and it required years of analysis to bring him to where he is today. The end.

Compared to the millions of kids going to bed hungry every night, one might not be inclined to give much weight to the suffering of the rich and famous. That is to ignore, though, the uniquely uncomfortable pedestal the public puts them on, and the practically mythic lessons to be derived from their travails. That the poor suffer is a given. That someone on entertainment Olympus was miserable might suggest that dreams are better directed elsewhere.

Cassidy comes across as a likable guy, but there’s no mistaking him for the guy next door. When he talks, he seems to be running on TV talk-show time, speaking in compressed, run-on sentences, as if he’s trying to get everything in before the commercial break.

In “Blood Brothers,” he said, he’s found a role that not only reasserts his acting ability but also “is the reason I got into all this. It’s a wonderful part. Examining it and living it in playing this guy’s life, it’s never ceased to be interesting and exciting and the reason why 25 years ago I decided as a teen-ager to become an actor. It was to be able to do exactly what I get to do with this.

“I’ve never played a part onstage before longer than six months, and usually by the fourth or fifth month you’re looking at your watch going, ‘Gee, this has been fun, now what?’ But I played this for 10 months on Broadway, and now on the road for another four months. It still not only is exhilarating for me to do it, but I feel I still haven’t gotten to the bottom of it.”

He credits the reality of the character to author Russell’s working-class Liverpool background. He finds parallels between the play’s Mickey and his own childhood. Despite his famous father, Cassidy grew up far removed from a Hollywood atmosphere, in East Orange, N.J. His parents divorced when he was 5, and Jack Cassidy, who was not yet an established name, was none too steady with his child support payments, according to David’s autobiography.

“Contrary to public opinion and the image people have of me, I grew up in a very lower middle-class, blue-collar environment 40 minutes outside of New York until I was 11. I came from a family and economic sort of consciousness that was very much the same as this character.

“I’m a very compassionate person, and this guy’s life is a microcosm of a lot of people’s lives that I witness on the street. It’s a downward spiral, and we’ve seen it happen more and more as the middle class has evaporated in America,” Cassidy said.

His personal upward spiral began at age 18, when he was cast in a Broadway play called “The Fig Leaves are Falling.” It wasn’t a success, but the experience led to guest parts on TV shows. Then, in 1970, came “The Partridge Family.”

Patterned loosely on the real-life Cowsills band, the show about a lightly rocking family (with a cast including Cassidy’s stepmom Jones) touring in their bus and righting wrongs was a hit, especially with young viewers. Cassidy was singled out and groomed for pop stardom, much as the show’s makers had manufactured and marketed the Monkees a few years earlier. Fronting the Partridge Family, he had three Top 10 singles, including the 1970 No. 1 “I Think I Love You,” and further hits as a solo artist.

His fan club amassed more members than the Beatles or Elvis Presley’s had. His “life-sized kissable” photo was the prime draw in teen mags. His concerts were wild scream-athons; at one British show a young fan died, asphyxiated in fans’ press to be nearer their star. Girls camped outside his house and the TV studio to get a glimpse of him.

He doesn’t deny making the most of it at the time, but it wasn’t exactly what he’d been aiming for.

“I didn’t know how significant the decision to do the show’s pilot was when I was a 19-year-old actor trying to pay the rent. My dad had said to me, ‘You do everything you can. You take every job you can, and hopefully you won’t have to be a waiter to support yourself.’ And I was able to do that at 19 years old, supporting myself solely as an actor, which is remarkable at any age.

“But I had to have my arm twisted by my agent to do ‘The Partridge Family’ pilot. It wasn’t creatively exciting for me to do. But I thought, ‘They make 50 pilots a year and only 10 sell, so what are the odds?’ Who knew what was going to happen? I certainly didn’t.”

While some, as perhaps Elvis did, go a little nuts when faced nightly with thousands who treat you as a god, Cassidy said that wasn’t a problem for him.

“It is difficult to be famous and that successful where you can’t even walk down the street without people chasing you, and having people build monuments to you and worshiping you--all that stuff--but I never took that to a place where I believed it. I saw it as being temporary and a phase.

“So that wasn’t so tough. What was tough was the way people my own age would perceive me as this image that was created of this sweet, innocent boy next door, which was the antithesis of the teen-age life I had lived. I hitched up to Haight-Ashbury in the Summer of Love, you know? And I was very much politically aligned with that whole mentality, the whole ideology of that generation, the music, the culture, the behavior.

“There was a generation from 16 down to 5 that thought I was the hippest thing that walked. But for people 16 and above--as happens to anyone with a label attached to them--they were too sophisticated for that.”

Cassidy’s first attempt to break free from that label came in 1972, when he granted a writer from the then very hip Rolling Stone magazine unprecedented access to his backstage life. The resulting article--accompanied by a two-page, pubic-hair-revealing photo taken by Annie Leibovitz--portrayed him alternately as a cynically packaged retail ware and as a stoned, drunk, expletive-emitting womanizer (Cassidy denies being stoned and drunk, saying that wasn’t part of his life then). The article, as might be expected, disillusioned some of his young fans while currying little favor with Rolling Stone’s regular readers.

While he was stung by others putting him down, Cassidy said he was doing the same to himself.

“A lot of my friends were the hippest, most cynical people. They knew me and were very protective of me. But those that didn’t know me certainly saw me as un-hip. And that was the most difficult thing, because I really aligned myself with them . I was in a way apologizing for making the records and being an actor in a television show that was geared more toward a light family audience. What a silly thing to have to apologize for, to be so successful. ‘Gee, I’m really sorry. Sorry I’m not unsuccessful and hip and not slashing my wrists.’ That would be really important. Having 25 million people think your work is great and that you’re a positive role model is something I shouldn’t have been proud of, right?”

He’s at peace with his past now and thinks people shouldn’t be so derisive of juvenile tastes.

Said Cassidy: “We, as adults, tend to say, ‘Oh, it’s that kid stuff. It’s just insignificant crap.’ But it isn’t insignificant at all. Kids need role models, whether it’s baseball players, actors or musicians, people to bring a little positive light into their hearts and minds. We need to be a little kinder to those people because it’s not easy being that role model, looked upon as something we are all incapable of being: too perfect.”

In 1974, before his stardom had run its full course, Cassidy walked away from it, retiring from touring as the show left the airwaves. He found it dogged his footsteps, though.

“I wanted to move on and find out what else was there for me. But people saw me as this character I created, and I guess I must have been pretty convincing because people certainly bought it. And when I stopped, I got the feeling it had robbed me of the opportunity to do what I had really wanted to do, which was to be an actor. Suddenly, at 25, I was put into a situation where I couldn’t get people to see me as just an actor. I was this . . . thing , this thin and shallow label that people wouldn’t look behind.”

As with other unwary teen idols, most of the profits from his efforts had eluded him. He had earned millions from his concerts but found that money had been embezzled or lost in poor investments.

Cassidy characterizes the time after his stardom as his dark years, full of excessive drinking, two failed marriages and record deals gone sour.

These days he says he’s considering another Broadway-bound production, a TV pilot and an album of Sinatra-style music once his road stint with “Blood Brothers” concludes in May. He credits five years of analysis and his marriage to Sue Shifrin (the couple have a young son) with bringing him back to his present fulfilled, life-loving attitude.

Not that being in a hit show hurts either.

“I’ve never been in a piece of theatrical work that has this kind of effect on an audience,” he enthused. “It never ceases to amaze me how people respond to ‘Blood Brothers,’ how moved they are by it and how it draws them in. It’s great to be doing the sort of work I’ve always wanted to. Not being able to for so long was demoralizing on a lot of levels, but on the other side, it makes success very sweet.”

* What: “Blood Brothers,” a musical by Willy Russell.

* When: Tuesday, Feb. 7, through Feb. 10 at 8 p.m.; Feb. 11 at 2 p.m. and 8 p.m.; Feb. 12 at 2 p.m. and 7:30 p.m.

* Where: The Orange County Performing Arts Center, 600 Town Center Drive, Costa Mesa.

* Whereabouts: San Diego (405) Freeway to Bristol Street exit; go north. Turn right on Town Center Drive and park in one of the lots.

* Wherewithal: $19 to $47.

* Where to call: (714) 556-2787.