Alrighty, well, with two positive votes and no naysayers, I'll post up a link or two every so often. Don't want to flood the thread, or overwhelm folks with a wall of links.
http://europe1.yiffstar.com/index.yiff?pid=6206
Up first is "A Dragon's Tangled Web" main character isn't quite human to start with, she's a golden half dragon. In DnD terms that means she's a shimmering, sparkling champion of good and righteousness.
So of course that makes it all the more interesting as a monstrous spider-dragon seduces her and transforms her into his mate.
I think this is probably the story of mine that most fits the thread.