If you haven't read DAVID:The Penance List by Siobhan Cunningham, you might want to pick up a copy. Here's my review:
The Penance List is a compelling psycho-thriller. I found myself snatching it up every chance I could, wanting to see what David would do next. The book is dark, naughty...at times downright nasty. Cunningham's first novel will hold your attention until the very end.