Have you ever had an idea for a book that didn't involve D/s or erotica in general?
Oh, absolutely - tons, in fact! I've written quite a lot of non-D/s over the years, and a couple of the books I've taken down and am in the process of rewriting have been non-D/s (though I'll admit that's changing in the case of one of them!).
As for books that don't involve erotic stuff at all, I have had many ideas, and even have books half-finished that don't have any sex in them. But they don't tend to hold my interest the way the erotic books do. At heart I'm too much of a romantic to keep things platonic between all my characters, and I always feel a little cheated in books when I get invested in a couple but then only get a fade-to-black scene when they have sex.
Eventually I'd love to write a book I'd feel comfortable showing to my parents or publishing under my real name, but at the moment I just have too many romance book ideas to work on!