Much is currently being made of E.L. James' steamy novel, "50 Shades of Grey," and its ever-expanding fanbase of mostly female readers. The novel, which is out in paperback Tuesday (April 3), started out as "Twilight" fan fiction; as such, it has several elements that lend themselves to comparison with Stephenie Meyer's YA saga.

First, there is the protagonist, insecure and naive beauty Anastasia Steele, who doesn't know she's attractive until she meets Christian Grey, a controlling older man with a magnetic personality. Apparently James took Bella and Edward from Meyer's world and placed them a few years in the future in non-paranormal-influenced Seattle; she called the book "Master of the Universe" online. "Shades of Grey" is hitting all the notes that Meyer's series hit when it entered the pop culture zeitgeist. It's a New York Times best-seller, will soon be a feature film and has been dubbed "mommy porn." Yes, I know that "Twilight" isn't "mommy porn" and that "Grey" isn't simply a very adult version of "Twilight," but the similarities are there.

So what does this mean for the publishing industry and the fan-fiction community at large? In this week's "Twilight" Tuesday, let's explore the increasing popularity of fan fiction.

First off, for the uninitiated, a lot of fanfic is racy. Like NC-17 and XXX-rated racy, so as much as I want to I can't post excerpts here. Slash fic, stories that feature same-sex relationships between two characters, can be particularly explicit. And though those tales probably won't make it to store shelves, the idea of an Edward and Jacob or Edward and Jasper romance is pretty entertaining.

"Twilight" author Meyer seems to have mixed feelings on the subject, but she has admitted to enjoying a few authors and entertained an alternate universe of sorts herself for "Twilight" in a project she calls "Breaking Down."

"In the beginning I hadn't heard of it. ... I couldn't read the ones that had the characters in character," she once said during an interview with Twifans.com. "It freaked me out. There was one about 'Harry Potter' and 'Twilight' that was hilarious. And then there was one that was about a girl who was starring as Bella in the movie and that was funny."

Meyer's "Breaking Down" was a crutch to help her get through finishing "Breaking Dawn," a place where she could let loose with outrageous scenarios for her mostly straight and narrow characters.

"We came up with an alternate 'Breaking Dawn' called 'Breaking Down.' It was awesome!" she said. "Complete spiraling downward and destruction in Bella Swan's life and everyone around her."

Naturally, Meyer didn't publish that alternate "Twi"-verse, but there are other cases of famous authors who began their careers writing fanfic; take Cassandra Clare, who wrote a popular spin on "Harry Potter" called "The Draco Trilogy" long before she came up with "The Mortal Instruments."

We could also count Seth Grahame-Smith's best-seller "Abraham Lincoln: Vampire Hunter" as a form of fanfic, along with the various "Pride and Prejudice"-inspired books like "Mr. Darcy Takes a Wife" and "Mr. Darcy's Diary: A Novel."

Authors who have negative opinions of fanfic make the argument that they own their characters and that aspiring authors should come up with original work. So where do we draw the line, and more importantly, should it be drawn? As long as we're getting more people to read, does it matter? Or is there a quality over quantity argument to be thrown in as well?

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