For centuries, readers have been inspired to write about the characters they love. Hephzibah Anderson looks at a popular − and eccentric − literary phenomenon.

Edward Snowden, Twilight’s Edward Cullen and Edward Kenway, a pirate from the Assassin’s Creed video games, share more than just a forename. All three turn out to be the subjects of fan fiction. In the past few years, this zany literary subculture has been undergoing a paradigm shift. It first achieved widespread exposure when it emerged that EL James began her Fifty Shades of Grey trilogy as fan fiction about Twilight’s Edward and Bella. Since then, Amazon has lent such works legitimacy via Kindle Worlds, a dedicated fan-fiction platform that enables writers to get paid for their work while also giving the characters’ creators a share of profits, and has seen published bestsellers like Hugh Howey, LJ Smith, and Kevin J Anderson writing their own fan fiction.

Featuring characters from novels by Kurt Vonnegut alongside vampires and superheroes, Kindle Worlds also gestures to the form’s breadth, but just barely. It remains far bigger and wackier than any but the fully initiated might realise. It has its own customs and mores, its own diverse traditions and its own terminology. (A ‘drabble’, for instance, has nothing to do with the author of The Millstone, instead referring to works just 100 words long.)

Thanks to legions of largely amateur keyboard-pounders, characters from books, games, TV shows and comics can be found breaking free from their original plots, periods and landscapes. They get to mingle (and rather more) with one another in ‘crossover’ fan fiction; they gain and lose magic powers in ‘alternate universe’ fan fiction; and they find themselves facing gritty challenges in ’angst’ fan fiction. You’ll find figures borrowed from the classics, from blockbusters and even from the Bible. From Beowulf, and Donna Tartt’s Secret History to assorted Tom Clancy tomes – all have inspired readers to become fan-fiction writers.

Fan fiction is commonly traced back to the 18th Century, when aficionados of Daniel Defoe’s Robinson Crusoe, wanting more, decided to write it themselves. Defoe was furious and likened it to kidnap. Novelist Michael Chabon has dated it back even further. To a degree, he has said, "All literature, highbrow or low, from the Aeneid onward, is fan fiction."

Anne Jamison, associate professor of English at the University of Utah and the author of Fic: Why Fanfiction Is Taking Over the World, agrees. “It is really much more what storytelling and literature looked like for most of history,” she says. The rise of individualism and the post-Enlightenment notion of genius pointed the way to obscurity, but the real reason for its exile, she explains, has to do with the idea of intellectual copyright.

Legal ease

Amazon has offered a way around that. According to Philip Patrick, Publisher of Kindle Worlds and Director of Business Development, their ambition from the very beginning was to solve a problem for writers.

“Until now, selling stories set in someone else’s World has been a big challenge. So we’ve worked with licence holders to acquire licences to open up their Worlds to other writers, who can then legally write and publish new stories set in that World and earn royalties from every copy sold. We think it’s a win for everyone involved – the World licensor, the writer and ultimately the fans who love these stories.”

In the nine months since it launched, 430 stories have been published, garnering 1,700 reviews with an average of four stars out of five.

Not that fan writers haven’t been critical. Initially, there was concern that Kindle Worlds would create a zone of permission, leading to a crackdown on the unauthorised fan fiction that existed outside that zone. So far, that hasn’t happened.

The idea that those properties control what can and can’t be done (Amazon has submission guidelines) also struck many in the fan fiction community as anathema. As Jamison points out, a key role of fan fiction is to do the things that the creators wouldn’t or couldn’t. “Fan fiction was one of the first places where you saw gay romances. It was also a place where people who couldn’t write very well would publish.” Creativity seems not to have been inhibited either on Kindle Worlds itself or elsewhere. Meanwhile, if you log on to, you’ll find a vast spectrum of literary prowess and, yes, lack thereof.

The most important of recent developments, Jamison suggests, is the increasing ease with which fan fiction is being accepted by mainstream publishing – or at least the promise of future acceptance. The prospect of monetisation breaks a sense of trust and goodwill that has long had people in the fan fiction community donating feedback, ideas and artwork to writers.

Gender gap

Until now, Jamison points out, there's been a distinct gender breakdown between those who write fan fiction – largely women – and those who get paid a lot of money to make adaptations of existing works that we don’t call fan fiction – largely men.

“Joss Whedon’s The Avengers – it’s not like it’s his story, right?” Jamison asks. “He did a great job with it, but then you can do a great job with an existing story. [It’s the] same thing with Sherlock Holmes. These men [who adapt existing works] are not being derided for being unoriginal in the same way that fan fiction writers are, even though a fan fiction story could have much, much less to do with its source.”

Debra Anastasia’s Poughkeepsie series is a good example. It all began in 2009 with Twilight. “I’d always wanted to write a story, but before fan fiction it seemed way too scary,” she says. “I fell down the wormhole after reading that Stephenie Meyer had herself written a bit of fan fiction.”

An average American ‘soccer mom’, Anastasia liked the anonymity combined with the thrill of instant feedback, and wrote her first four chapters in one night. “I’m not sure if I would have made it to the end of the story without the reader participation and encouragement. Poughkeepsie had over 3 million hits when it was online.”

Poughkeepsie is categorised as 'All Human', meaning that the characters’ supernatural traits are stripped from them. Unlike Meyer’s original, it also features some decidedly adult content. And like EL James, Anastasia used the names Edward and Bella when she was writing online, though almost everything else is radically different.

When fans suggested Anastasia publish the work as a book, she began approaching agents and mainstream publishers. Her experience was, she admits, “resoundingly negative,” but she’s since gone on to publish four novels with Omnific Publishing, a company that itself sprang from the fan fiction community.

While its popularity raises important questions about originality and our apparently insatiable appetite for remakes and sequels, it’s also a place for vital experimentation. It can teach aspiring writers plenty, too.

“Fan fiction was my university,” Anastasia says. Jamison agrees. Having previously studied with Joyce Carol Oates and Russell Banks, her forays into fan fiction taught her plenty more about how to connect with readers.

Not that it’s easy. Expert though she is, Jamison simply couldn’t make her Buffy-Twilight crossover fiction work. “I didn’t really like Twilight, so I couldn’t really write a fan fiction. All of Edward’s bits were Byron. Let’s just say I’m not getting the Fifty Shades cash for that particular effort.”

If you would like to comment on this story or anything else you have seen on BBC Culture, head over to our Facebook page or message us on Twitter.