A sexy young lady of enigmatic beauty and a hot, gorgeous young billionaire - these are the central characters in E.L. James' "Fifty Shades of Grey" and Sylvia Day's "Crossfire" erotic series.

Fifty Shades, which tackles sadomasochism, took its roots from being a fan fiction of the "Twilight" series by Stephenie Meyer. Crossfire, on the other hand, is widely believed to be inspired by Fifty Shades. Day denies ripping off James' work, saying that she completed the first Crossfire book in December 2011. Fifty Shades, meanwhile, went mainstream in March 2012.

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A film adaptation of Fifty Shades is currently being worked out by Universal Pictures and Focus Features. The production outfits have yet to name their lead stars. Fans have just been casting their choices for some months now. When the Crossfire series started charting on the New York Times bestsellers, fans speculate a movie version could eventually develop for Day's work, too.

For Gideon Cross, the male lead in Crossfire, the same Christian Grey potentials are being named by fans: Matt Bomer, Ian Somerhalder, and Henry Cavill among others. Fans claim these actors have the requisite demigod vibe for the role.

It is quite different with the ladies, though. Some of those who have topped previous polls for the role of Grey's Anastasia Steele include Alexis Bledel, Emma Watson, and Game of Thrones' Daenerys, Emilia Clarke. But there is a significant difference between Steele and Crossfire's Eva Trammel. Steele starts off as a 21-year-old intern, an (unbelievable) virgin, who first saw Grey as her very own prince charming. Trammel, 24, daughter of billionaire parents, is a child abuse victim. She laughs at the idea of a prince charming. And she is not exactly the submissive type.

Here are the actresses fans are pegging for the role of Anastasia Steele.

Alexandra Daddario - Alex played opposite Matt Bomer in the TV series White Collar. Her character Kate has been killed off, but her screen chemistry with Bomer lives on. She'd be more convincing as Trammel.

Emma Watson - Emma has proven she is a brilliant film actress. But with those fierce eyes and a natural take-charge vibe, she might not be convincing as Ana. She can rock Trammel.

Alexis Bledel - A recent poll by Latinos Post showed Alexis as the top fan choice for the role of Ana. She may be much older than the character, but she has the vibe that lies gracefully about her age. She can be a very convincing naïve-yet-lusty Ana.

Emilia Clarke - Emilia's character in GOT has gone from 'baby girl' to mother-of-dragons. This actress can play either role, but such talent better matches a darker character.

Amanda Seyfried - Amanda also has the genes that can play a twenty-something innocent. Her recent images in a Daily Mail report scream Ana Steele. But there is no doubt she can be a great Eva Trammel, too.

Click 'Start' to see photos of these lovely actresses.

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