> Neal Stephenson's The Diamond Age, where there's a
> minor character (BDSM is not a big part of the book)
The fictional character that came to mind for me--okay, there were two--but the first one that came to mind for me was the provocateur in _Neuromancer_ who seduces pretty young women into subversive activity, turns them in, and then helps to torture them.
(The other one, again from high-class science fiction, was the narrator of John Barnes' _Kaleidoscope Century_ and his partner-in-crime Sadi. Okay, there were three)
This is, of course, fiction. I suppose we could also drag in Hawk from "Time Considered as a Helix of Semi-Precious Stones" and run on from there.
All the best,
John A