By Annalee Newitz

THIS MONTH'S ISSUE of Harper's magazine includes excerpts from a juicy flame war between Judd Apatow (creator of Freaks and Geeks) and Mark Brazill (creator of That '70s Show). Both are known for their smart, mild-angst teen comedies. Brazill, the less successful of the pair, accuses his old friend Apatow of stealing an idea from him in the early 1990s, then goes on to proclaim shrilly, "You may not think you were a thief, but most comics know otherwise." This accusation, which Brazill considers utterly damning, hardly fazes Apatow. "Every writer in town has thought of [your idea] at one point," he replies.

And yet, whenever a great TV show like Buffy the Vampire Slayer wows the fans season after season, the critics blame it all on originality. The characters are exciting and new, they say, even if Buffy has existed multiple times before, in the guises of Wonder Woman and Bionic Woman and Xena and that chick from Dark Angel (oops, Dark Angel copied Buffy). But the plots are fresh, the critics cry, even if Buffy-esque dramas have animated everything from Dark Shadows to Twin Peaks.

Let's face it: Buffy – the show that launched two spin-offs (the Giles show, whose name is still to be determined, debuts on the BBC later this year) and several comic books (most notably the cyberslayer title Fray) – isn't original. More than anything, Buffy's strength has been the show's ability to reflect the obsessions of pop culture around it, rather than breaking new cultural ground. Buffy's popularity has depended on its ability to morph with the times, appropriating changing styles and attitudes in order to keep its audience mesmerized while sucking in new fans along the way.

Buffy creator Joss Whedon has woven his show out of cutting-edge ironic movie trends, dipping into recent horror-flick history to make a show that exudes the kind of ambient dark sarcasm you find everywhere in pop culture these days. Ever since American horror was Scream-ized in the mid 1990s, audiences can't get enough of sexy teen appeal combined with very adult eyebrow-arching at the ridiculous idea of a horror movie that could actually scare its jaded audience.

This isn't to say that Whedon ripped off the Scream series. But it's undeniable that the success of Scream paved the way for a gleefully nihilistic Buffy. Not surprisingly, Buffy became a kind of starting place for many other Sarcastic Edgy Teen projects. Sarah Michelle Gellar, the show's titular superhero, played a murder-victim babe in I Know What You Did Last Summer (1997) and a self-ironizing sex kitten in Cruel Intentions (1999); Alison Hannigan, who plays lesbian pagan computer geek Willow, did a memorable turn as a horny high school band nerd in American Pie (1999); and Eliza Dushku, a.k.a. evil vampire slayer Faith, positively scorched the screen as a bad-girl cheerleader in Bring It On (2000).

The Scooby gang's deadpan "it's another earth-sucking demon again" attitude is perfect for a generation that grew up with high school shootings and seemingly random acts of international terrorism. Air-quote violence isn't a trend that Buffy started; it's simply a trend that the show has demonstrated in a particularly appealing way.

Buffy also owes its sensibility to thousands of fanzines, "shipper" Web sites, and plain old fan activism. Buffy is at the forefront of an entertainment trend that puts fans in the driver's seat, at least in part. While Star Trek fans of the '70s and '80s pounded their heads against the wall of Roddenberry and Co. trying to get this or that aspect of the Star Trek universe changed, fans these days often get the royal treatment.

Whedon (Joss to the fans) often visits fan discussion sites to see what people's responses are to the latest episodes of Buffy and Angel, and he's even been known to post comments on occasion. If a character or plot cycle on Buffy is particularly heinous to the fans, there's a good chance it will change. And Buffy "shippers" – fans who write fiction or create movies about certain characters having relationships with each other – are possibly the most rabid and influential. Buffy-Spike shippers are in ecstasy right now because after they lobbied for years to get Buffy into bed with bad-boy Billy Idol look-alike vampire Spike, it's finally happened. The two are having a nasty, secret relationship full of handcuffs and tainted love.

The growing power of fan culture started, like all good things, with the Internet. Since fans have swarmed into interactive forums online, their numbers have grown, as has their ability to organize in the name of pretty much anything. A fan culture turning point came several years ago when the Knighties – fans of canceled Canadian vampire-detective show Forever Knight – launched a campaign to bring back the show. Although the network never did resurrect the adventures of Nick Knight and his lab-geek gal pal, massive media coverage of the fan campaign demonstrated that fan culture was becoming a force to be reckoned with. The Knighties clearly influenced Buffy spin-off Angel, whose titular character is a guilt-ridden ex-bad guy who fights crime, just like Nick Knight. There was even a cameo by one Forever Knight regular (dressed en vamp) in an early episode of Angel.

More recently, the Lord of the Rings movie was practically a fan-authored production. Director Peter Jackson and his team combed LOTR Web sites looking for fan responses to plot changes they proposed for the big screen. When fans responded negatively, Jackson didn't hesitate to rewrite portions of the script. In fact, the only thing fans didn't like that remained in the movie was Liv Tyler – and the critics hated her too. Score another one for the fans!

And score one for the Buffy empire, too, which, thanks to fandom, sprouts new tentacles every day.

For the fans, nothing can equal the sheer lovable weirdness and, yes, pathos of this season's recent musical episode, titled "Once More, with Feeling." There were disco dances, rock ballads, and ensemble pieces with dancing meter readers. Spike sang about his tormented desire for Buffy, Tara sang a love song to her girlfriend, Willow, and luckily, when Buffy's little sister, Dawn, started singing, she was quickly stopped. It really was marvelous and bizarre and all the things you wish that TV would be if you were ever a fan of Twin Peaks.

And, like many parts of the Buffy universe, it was a tip of the hat to something else, a new trend in pop culture. Right now we are witnessing the rebirth of the musical with movie successes like Hedwig and the Angry Inch and the more conventional Moulin Rouge, and so, naturally, if Buffy is going to keep up with "hip," the show must convince us that it is cool enough to sing.

Then again, I'm not sure we really needed convincing. I can't wait to read the comic book version of the original Buffy movie, and I'll be there when the BBC premieres its spin-off with Giles. Perhaps as fan culture becomes more powerful, it will inspire the creation of more TV shows that are built to make fans out of us all.