In a nutshell, the book is 500 pages of light BDSM (bondage, discipline, dominance, submission) scenes mixed in with an even lighter "vanilla" love story. Ana is a 22-year-old recent college grad and virgin who falls for 27-year-old billionaire Christian Grey, who smells of "body wash" and danger. Christian's into some "kinky" stuff -- spanking, cuffs, clichés -- and Ana gets dragged into his lifestyle. Most of the book is spent in young Ana's head as she battles with her "inner goddess" and "medulla oblongata" over the morality of Christian's freaky fetishes.

Zane's Sex Chronicles and Addicted can satisfy a woman's fantasies just as easily. The difference is all about agency. In Zane's books, the female characters already know what launches their lady rocket. In James' Fifty Shades, Ana is the female embodiment of a blank slate. The women of Zane's fantasies are idealized: career driven, smart, financially stable and independent.

In a rare profile of Zane in 2004, a New York Times reporter called the author's characters complex and "aspirational": "Rarely is there a shortage of suitable African-American men for the aspirational women in her stories, and when women travel down the economic ladder to couple, they are not forced to do so, but choose to."

By contrast, James' "submissive" Ana leaves everything up to her "dominant," Christian. The fantasy, the big payoff, is that he shows up and, just like Brian McKnight sang in his "adult R&B" song  "Ready to Learn," shows Ana "how her p---y works." A Zane heroine would already know.

So what does that say about the differences between African-American and white female erotica fans? Each demographic has made a millionaire out of the woman smart enough to tap into them. But what, exactly, have they tapped into?

The idea that black women are seen as strong, take-the-bull-by-the-horns-type heroines and white women are seen as damsels in distress is nothing new. What's interesting here is that the women themselves seem to be buying into pop culture's own depiction of them, adopting the fantasy as their own.

The opinionated black CEO who has her way with the delivery guy and then sends him on his. The quiet white college grad who lets someone else take the reins and then smack her with them. Neither is a groundbreaking concept, and yet both have hit a pipeline to the way different women see themselves in their fantasies.

Helena Andrews is a contributing editor at The Root and author of Bitch Is the New Black, a memoir in essays. Follow her on Twitter. 

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