In April 2019, the romantic drama After was released in theaters nationwide. It tells the story of a troubled relationship between a college freshman, Tessa Young (played by Josephine Langford), and a young man with a secret, Hardin Scott (Hero Fiennes-Tiffin). As of this writing, the movie has been a financial success, racking up more than $58 million on a $14 million budget.

Viewers aren’t flocking to see After because of its cast of near-unknowns but rather because the movie is based on a very popular 2014 novel of the same name by Anna Todd—which, in turn, was a rewrite of Todd’s wildly popular fan fiction series, self-published on the site Wattpad. Todd’s original stories were viewed more than a billion times, and many of her readers had one big thing in common: they were fans of the English-Irish pop band One Direction (1D).

Why were 1D fans attracted to Todd’s series? Because the Wattpad version of After didn’t have “Hardin Scott” as its leading man. That role went to Harry Styles—perhaps the most famous member of 1D. The popularity of Todd’s fan fiction led to a publishing contract with Gallery Books, a division of Simon & Schuster, in 2014 (with the character names changed, of course). After is just the latest example of fan fiction leading to mainstream publishing success.

What is fan fiction?

In fan fiction, writers take characters that they love—from books, TV shows, movies, or other parts of popular culture—and self-publish their own stories about them on sites such as Wattpad, Archive of Our Own, and FanFiction.net. The work is shared with other fans for free.

The writers often add new elements that the source material didn’t explore; this means changing the setting, adding new characters, or addressing themes that the original never did. Some, though certainly not all, delve into the realm of erotica; for example, some early Star Trek fan fiction in the 1970s envisioned a romantic sexual relationship between Capt. James T. Kirk and his first officer, Mr. Spock. E.L. James wrote sexually explicit Twilight fan fiction that she later self-published, with character names changed, as Fifty Shades of Grey; that novel, and its sequels, were picked up by Vintage Books and became massive worldwide bestsellers—and blockbuster movies.

Why write fan fiction?

Fan fiction writing has proven to be a great way for emerging writers to hone their craft or for established writers to be creative outside their usual genre. Cassandra Clare, who wrote the bestselling YA series The Mortal Instruments, has previously written Harry Potter fan fiction, for instance, and S.E. Hinton, who’s best known for her classic novel The Outsiders, has written stories based on the CW TV show Supernatural.

Fan fiction itself may be headed toward a lucrative future, as well. For a few years, until August 2018, Amazon.com ran an online store called Kindle Worlds, in which fan fiction writers could sell their work on Amazon without changing the character names—provided that the company had a licensing agreement with the makers of the underlying work. If you wanted to sell your Veronica Mars, Pretty Little Liars, or Gossip Girl fan fiction, for example, you could do so. One could even write fiction using the iconic author Kurt Vonnegut’s characters—an intriguing prospect. (Slaughterhouse-Six, anyone?)

It’s a model that’s full of possibilities, and one that other companies may be willing to explore, given the huge potential talent pool. Archive of Our Own, for example, hosts some 4.8 million works of fan fiction alone, drawing on more than 32,000 fandoms. And if the success stories of Anna Todd and E.L. James have proven anything, it’s that the right fan fiction can find a very wide audience. Who knows? Some brand-new startup might end up hosting the next After—written by the fan fiction writer next door.

—David Rapp is the senior Indie editor.