BLACK JEWELS TRILOGY! I have been obsessed since I was...fourteen (so eight years?) I still do my yearly reread, and with the new books coming out it's been so much fun! No idea about a fandom, but I did write a BJT story for Yuletide so I know there are at least some fanfics over there.

I personaly love Saetan more, but I was faced with your dilemma for a long time before I realized I just couldn't help but love his dry sense of humor :D