To get a book turned into a movie, the author must try to sell his or her movie rights to a studio. I say "try" because there is no guarantee that anyone will buy the rights. LJ Smith's work got picked up right after Twilight because TV studios wanted something to bring in that fanbase. She had to wait well over a decade and for a huge boom in vampire popularity for that to happen (and she still gets accused of ripping off Twilight, which simply gave her work new relevancy).
Once movie rights are sold, there is still no guarantee that anything will come of it. The author does not have control over any part, up to and including major plot changes. The rights belong to the company that bought them and that company can twist and mutate the story any way they want. (Which is how we got that terrible bastardization of Ella Enchanted.)
In fact, if anyone makes book movies happen, it's fans. By being rabid and many and full of ticket sales.
|And creepy. Don't forget the creepy.|