“Fifty Shades of Grey” devotees, know this: Whether you end up loving or hating the new movie, author EL James had your back. “I was thinking about the readers,” James says about the sometimes fraught process of adapting her steamy book to the screen — a process that reportedly involved creative differences, to put it gently, with director Sam Taylor-Johnson. Out this Friday for Valentine’s weekend, the R-rated film stars Dakota Johnson and Jamie Dornan.James says, “I understand what it’s like to be in fandom. I had to fight for a lot of things really hard. And I did.” As a producer on the film as well as the trilogy’s author, James had an unusual amount of creative clout. James, 51, wrote the erotic trilogy for her own enjoyment and ended up launching a global phenomenon.