Fifty shades triology is a story about Christian Grey, a very successful Entrepreneur and Anastasia Steele, a lady who happened to unexpectedly stumble into his life.
What sets this book apart from others is its sex scene.
Christian Grey only engages in bdsm sex style. A sex style portrayed by the society as immoral. Though a man can voice out his love for bdsm but a lady is much more quiet on this as she doesn't want to be seen as a slut and a tool to a man's satisfaction even though she badly would like to engage in it.
This is where E.L JAMES - Fifty Shades Of Triology comes to play. She brings out that wild desire every female would like to have. She puts it into action with vivid description of how it feels like. Ladies can put put themselves in place of Anastasia Steele and feel that sexual climax she undergoes.
But we focusing on the success of the book basically on it for being about bdsm will be an understatement.
Firstly her choice of diction is one which goes hand in hand with the contemporary time. People are no longer into sexual metaphors. Call a spade a spade, and that is what E.L James did.
Ex: "he cupped her breasts in the whole of his hand then wound his tongue around her areola, his tongue lashing on her nipple" - Fifty shades diction type
Ex: "he wrapped his fingers around her bossom and trailed his tongue around the edges near the pointy tip of her bosom which were now firlmly erect" - 20th century diction type
We are no longer in the 20th century were writing breasts, vagina, nipples were seen as immoral. The tines have changed so change with it.
Secondly, her language. She didn't make use of overly rich language filled with floweriness. Her language was that which we use everyday.
Ex: "the hell is wrong with you"
Ex: "so are you gonna stand here or move your ass"
It's said the most successful books ate those which mimics the everyday life of people which they can easily relate too.
Thirdly, she made her male character independent financially and emotional. This also can be seen in Twilight. And they both are financial successful novels which were turned into movies. Even though most critics compare the female characters as dependent ladies who only see a forwardness in their life by clutching to a man, one thing you should notice is those two novels are much more successful than novels which creates and independent and strong lady.
In real life most ladies are not that independent and strong and clutch to men for emotional support so it's easier for them to identify with the two novels.
So, I'm short, make your male character a strong and independent man while the lady is subordinate but still have a life of her own.
While the above listed will also guide you on creating an erotica fiction like fifty shades of grey, don't forget that the sex part counts a lot. Stop giving sex scenes of missionary style, cow girl or doggy. Start creating unconventional sex scenes like fisting, outdoor sex and so on.
Happy trip towards writing your very own erotica fiction.