Honestly? This: Killing Show It's technically BL, but if you manage to last until there's BL, I don't think you'll mind...
Its hard to find TRUE Insanity, that isn't just "Evil" called Insanity to justify the author. Surprisingly The Wandering Inn has a few characters you could call Truly Insane, though they're not the MC (Even if the MC is a Liiiiiitttle insane).