I never got to play him, but during 3.0 I had an idea for a Cleric who had the domains of Knowledge and Madness who was eventually to take the Alienist prestige class. His backstory was that he had been forcibly abducted and recruited into an occult order called the Prisonkeepers, a group dedicated to the imprisonment of a Cthulhuesqe entity. Where other Clerics are granted powers by their Gods, the Prisonkeepers drained away the power of their imprisoned God, preventing his escape, by rituals that were the spiritual equivalent of Divine rape. This, and the nature of the energies they were channeling, eventually would drive each of the prisonkeepers completely insane - but they viewed their sacrifice as necessary to keep the horror trapped.
It was a pretty messed up idea that I never got to run.
It was a pretty messed up idea that I never got to run.