The difference between the author of the above and other Potter fans is that his appreciation doesn't end when the books do. Instead, he writes new stories using the characters, locations and plots in the Potter books and posts them on the internet to be reviewed by other writers of so-called fan fiction.

"When writing fan fiction you add your ideas to an existing world," he says of his hobby, which has taken off since Harry Potter arrived on the literary scene.
"You can use existing characters and places, or make up your own. The only thing you really have to look out for is to stay within the 'rules'. If there is evidence in a book of something not being possible, it's generally a good idea not to do it.
"For example, in J K Rowling's series I believe Professor Dumbledore says that you cannot bring back the dead, so you probably shouldn't write a story about a Dark Wizard studying necromancy. That said, Dumbledore could be wrong, and writing about the study of bringing back the dead could be a good writing experience."

Not all writers of fan fiction – or fics – adhere to the facts set out in the books that inspired them, however, and many take pleasure in changing much-loved characters, splitting up perfect matches and killing off heroes and heroines. So it is that Hermione moans about PMT, Lyra and Will of Philip Pullman's His Dark Materials make rather explicitly-described love under a tree and Alice from Wonderland becomes a rock star.

Mara Millman has been writing fics since she was 16 years old. Now 34, she gives advice and edits the work of younger writers. "As a mother and ex-teacher, it's wonderful to see these kids writing, even if it's fan fiction," says Millman, a published author who is from Kent but lives in south Florida. "Harry Potter got kids interested and a lot of the kids writing fan fiction now want to delve into original work, which is even more wonderful. I try to help out. I've put up lots of links about spelling, punctuation, grammar, everything. It's very important."
Millman is a fan fiction veteran, having written more than 200 chaptered fics on Harry Potter, and sees real hope. "Some of the kids out there today write better than I did back then," she says. "The problem with fan fiction is it's a disclaimer-based situation, so it's never going to be published because that would be infringing copyright. But online I definitely see it growing. Years after Harry Potter is off the shelf, it'll still be going on."