Alex Varkatzas is totally pissed off.

That's nothing new for the high-strung singer of Atreyu, who routinely lashes out in song about complacency, mortality and head games. But this time he's got a different reason to fume.

His band has just arrived at the Las Vegas club it's supposed to headline -- and the marquee lists Atreyu as the opening act, below From Autumn to Ashes. The fliers hanging inside feature Atreyu's name in tiny letters on the bottom of the page, and a local radio station recently announced that the show starred "From Autumn to Ashes plus guest."

"Everyone thinks we're some piddly-ass opening band," Varkatzas grumbles. "And our tour manager called in advance to tell them we were headlining and make sure this kind of sh-- wouldn't happen. And it didn't do a f---ing bit of good."

Such exasperation helps keep Atreyu's fire burning -- but circumstantial misfortune pales in comparison to the soul-rending stories of betrayal and breakup that have helped turn Atreyu into a major new force in heavy metal. Along with a host of other heartbroken, hate-filled noisemongers like Bleeding Through, From Autumn to Ashes, Every Time I Die, Unearth, Avenged Sevenfold, Poison the Well and Funeral for a Friend, they're turning headbangers on to music that's more cerebral, unpredictable, volatile and lyrically articulate than much of the nü-metal that has permeated airwaves for the past five years.

Dubbed "screamo" or "extreme" by those who invent categories for such things, the groups write scathing, turbulent songs rooted equally in hardcore, metal and emo. Typically they play aggressive, chaotic passages flush with larynx-shredding vocals, then balance them with swooping melodies and vocal harmonies. But while there's certainly a formula at play, it's not as predictable as the soft verse/ loud chorus formula followed by most neo-grunge acts.

"This is extreme music for extreme times," said Maria Fererro, an independent publicist who has worked with metal and screamo bands for well over a decade. "Metal isn't what it used to be, but 20 years later it's still about the same things. These kids are dressed differently, but they're still rebelling."

Over the past year, screamo has surfaced in a major way: just check out your local Hot Topic, turn on "Headbangers Ball" or leaf through the major metal mags. And Ozzfest has caught on like a shark following the scent of blood. The festival, whose second stage has proven to be the litmus test of all things loud -- it booked System of a Down in '98, Slipknot in '99, and the Used in '02 -- is making its boldest strides to date by enlisting screamers Atreyu, Every Time I Die, Unearth, Hatebreed and Throwdown for this year's festival.

"Before we left for a European tour with Chimaira, our manager told us he was putting in a shot-in-the-dark bid for Ozzfest," recalls Every Time I Die singer Keith Buckley. "No one had their hopes up or anything, so we just focused on the tour. Then, when we were on the road, we got a call saying it was looking real good, and by the time we got home it had already gone through. We were pretty blown away."

As thrilled as he is to go from playing small clubs to festival crowds, Buckley is shocked to be embraced by today's metal fans. Like many of his screamo peers, who enjoy elements of metal but align themselves more closely with the ethics and aesthetics of hardcore, he has little respect for stereotypical heavy metal.

"When I was younger, my older second cousin used to listen to metal, and it was all about big work boots, hair down to your ass and tapered jeans," Buckley said. "You'd enter your car at the crash-up derby at the county fair and listen to Guns N' Roses and Slayer. Compared to that, there's no way we're metal -- but today metal kids are [different]. ... Maybe the aggression and the energy we have in our music is something those people can relate to."

Screamo's progression to Ozzfest didn't happen in a weekend, and it required the right climate and circumstances to prosper. In the late '90s, while punk rockers were getting turned on by Slayer, Pantera and melodic Scandinavian metal, some rivetheads were discovering the social and political messages of '80s D.C. punk bands like Minor Threat, Fugazi and Rites of Spring. What followed was a rash of metallic but lyrically poignant hardcore outfits including Earth Crisis, Hatebreed, Neurosis and Cave In, which inspired a legion of other musicians to push the boundaries of both punk and metal styles.

On one side of the fence were more punk-oriented bands like Converge, Dead Guy, Coalesce and Botch. And on the other were metallic groups such as Killswitch Engage, Shadows Fall, Lamb of God and All That Remains. Different though they were, all were united in their efforts to experiment with the parameters of extreme sound. Then, as heart-on-sleeve screamo outfits including Thrice, Thursday and the Used poked their heads into the mainstream, the floodgates opened for the new breed to feed. Almost immediately, an audience tired of formulaic nü-metal began lapping it up.

"Some of that old metal sounded cool, but lyrically, none of those bands were speaking to us," said Bleeding Through guitarist Scott Danough. "So many of the new bands are singing about real relationship issues and personal sh-- that means so much more than the 'I'm harder than you' wall that a lot of the metal bands put up."

To Varkatzas, the growing popularity of screamo has more to do with kids getting tired of being spoon-fed trends, stereotypes and capitalistic values. "People want to be able to make up their own minds about things, and they want to feel like the music they listen to is written for them," he said. "These bands are doing better now because they have real sincerity and passion. Kids know the sh--'s for real. I'm not singing about cocaine and fast cars and bling and bitches and hoes. I'm singing about my everyday sh-- that everyone goes through. I can't relate to pimping it. ... I don't even know how to pimp it -- and there are lots of kids out there who can't pimp it, either."