Harry Potter looked out into the corridor and raised his wand. “Accio Blaster!” he shouted. The storm trooper’s blaster rifle flew out of his hands. Harry caught it. As the storm trooper stared at his hands in disbelief, Han Solo shot him.

Chewbacca made another growl.

A twist ending to end all twist endings? Not exactly.

Harry Potter and the Dark Lord of the Sith is a work of fan fiction, one of 300,000 Harry Potter tribute stories currently posted on FictionAlley.org. By now, thousands of readers are mourning the last page of Harry Potter and the Deathly Hallows with teary resolve. But those who refuse to be finished with this last book in the series will rush to their laptops to write new adventures involving Hagrid, Hermione and the rest of the Potterverse gang.

Deathly Hallows is the end. And it’s the beginning.

The Potter fanfic phenomenon took off between the release of Goblet of Fire and Order of the Phoenix — a Harry-less wasteland from 2000 to 2003 during which J.K. Rowling left fans desperate for the next installment of adventures.

What began as linear predictions of “What happens next?” has since morphed into fantastical postulations of “What else is possible?” Today, fanfic sites host stories about Harry teaming up with Buffy (crossover fic), Harry marrying Ginny (’ship fic, short for relationship) and historical fic about Dumbledore’s youth. Readers can even visit RestrictedSection.org for NC-17 nudie fic involving pairings from Trelawney/Flitwick to Neville/Giant Squid.

“The Harry universe is always expanding,” says Heidi Tandy, founder of FictionAlley. “Goblet of Fire made us realize the wizarding world went beyond England with (foreign schools) Durmstrang and Beaux-Batons. Order of the Phoenix made us interested in Harry’s parents’ generation.” Fanfic didn’t begin with Harry Potter. Anyone familiar with Rosencrantz & Guildenstern Are Dead, that rollicking spinoff of Hamlet, has read some already. The concept entered pop culture with Star Trek, when uber-Trekkies began to circulate mimeographed tales of Captain Kirk and Mr. Spock’s forbidden love.

And fanfic is not a critique on Rowling, whom the writers view with awe, so much as a critique on ownership in general. The Internet is a world of easy and unabashed appropriation, where original works are viewed as raw material made for molding rather than finished masterpieces to be studied. For the most part, Rowling shouldn’t worry about a dethroning anytime soon. The majority of fanfic stories are read by just a few hundred visitors on specialty sites. A lot of them are, frankly, bad — navel-gazing stories in which Hermione falls in love with an unassuming Xbox fanatic from Ohio, who sounds a lot like the story’s author.

But a lot of them are good. Addictingly good. So good, in fact, that some of the fans have gained fans themselves.

Sarah Rees Brennan, known online as “Maya,” is one of these “Big Name Fans,” as they are called. She began writing short fanfic as a teenager, for her own amusement and to share with her friends. By the time she tried a novel-length story, her fan base had expanded. The first chapter of Draco Malfoy, the Amazing, Bouncing ... Rat? garnered 48,467 Web hits.

After posting her second fanfic novel, Underwater Light, Rees Brennan, now 23 and a grad student in England, received a call from a stranger asking permission to tattoo its opening line on her back (“Harry Potter thought about himself as he entered the water.” Not an auspicious beginning, but the novel improves).

The legality of all this is a hot topic online; but for now, fanfic sites aren’t going the way of Napster, and as long as fic writers aren’t making money off their work, they’re in the clear. (Several Big Name Fans have used their Potter popularity to secure book deals for their own fiction.) And although many authors — most notably Anne Rice — are anti-fanfic, Rowling has said she’s flattered by readers’ interest.

In the relationship between the reader and a beloved character, the line between identification and ownership is thin and treacherous. At Lumos 2006, a Harry Potter convention in Las Vegas, a panel discussion was devoted to debating whether Hermione really would have confunded Cormac MacLaggen in Half Blood Prince, or whether Rowling made a mistake. Some Harry fans think they understand the Potter Pack better than Rowling herself.

This character commandeering is at the very (Hor)crux of the matter. It’s one thing to send Harry and Ron on a new set of adventures. It’s quite another to completely change who Harry and Ron are — or rather, who Rowling has decided they should be. Picture a Pride and Prejudice tribute in which Elizabeth Bennet is a gold digger.

Impossible, you say, for fanfic to usurp an original author’s canon?

Consider “Fanon Draco.”

Fanon is defined as a fact or belief that is used so much in fanfic that it is generally accepted as having actually happened in the fictional canon. Draco, the slimiest of the Slytherins, received a major PR boost at the hands of fanfic writers, who decided that his racist snobbery in the books belied a charming, vulnerable and lovable inner core. Now Draco boasts more stories on FictionAlley than any character other than Harry.

In a 2005 interview, the benevolent Rowling expressed dismay over the rise of Draco: “People have been waxing lyrical (in letters) about Draco Malfoy. ... It stopped amusing me and started really almost worrying me.”

Even Emerson Spartz, 21, who runs Mugglenet and is the preeminent source on all things Potter, has occasionally fallen under Fanon’s spell: “I’d be describing something, and my friend would say, ‘That never happened!’ I’d go, ‘It totally happened! It’s right here in chapter — Oh.’  ”

Consider another popular bit of Fanon: the passionate romance between Remus Lupin and Sirius Black.

What, you don’t recall that?

Refresh your memory by visiting Jaida Jones’s “Shoebox Project” on LiveJournal. Jones, 20, a student at Barnard College, has created a richer romantic history for the two men than Rowling ever could have using books alone. Her multimedia site features original artwork and handwritten letters. She has received e-mails from parents saying they read installments of the Shoebox Project aloud to their children indiscriminately alongside the Harry Potter books because it teaches lessons of tolerance.

The attention baffles Jones. She started her project only to find new ways to interact with the Harry Potter characters she loved so much. Fanfic taught her invaluable lessons about writing, she says, giving her the courage to pursue independent projects. She now has a novel in the works with Bantam, but she plans to finish the Shoebox Project — regardless of how the series ends.

In fact, even if the last sentence of Deathly Hallows reads, “And everyone died and Hogwarts exploded and the world ended,” there’s little chance that any fanfic writers would stop typing. The material is too rich. There are too many corners of Potterverse left to explore. There are spinoffs already in the works that may require further spinoffs, creating new