In the Blood (1995)

Don't bother getting this one if you're into gay vampires. The first half of the book appears to be a number of poorly written S&M fantasy stories that are all remarkably the same. The second half of the book is the start of a gay vampire story.

The story involves a 'force' that enters a single man and turns him into a sexual vampire. His power is to make anyone want to have sex with him and then be able to drink him dry of random things... generally muscle mass and dick size.

The story just stops after setting up a whole lot. To be fair, the author does warn that this would happen, but you have to wonder why he'd publish the story without finishing it.