I used to not be that interested in AUs because my reading (and writing) of fanfic is inspired by my interest in the characters on the shows, in the universes they exist in. So it was hard to imagine why I'd want to read about an non-vampire Spike, for example. But after reading some AUs by some really awesome authors, I realized that there's a lot of great potential to explore these characters in different settings. And I agree, mortal human Spike is really interesting to read and write about!