Insanity and Corruption.
No, not another rules module. Despite the readily apparent absence of Insanity Points et al, all the relevant (at least to me) elements are already present in Epic Roleplay, in the guise of talents (such as Hatred, Ignorant, Insanely Faithful, Mindless, Daemonic, Possessed) and careers (Cultist, Daemonhost, Mutant).
This, of course, does not exclude the possibility of having events and developments in play act as possible sources or triggers for gaining such talents or enabling (or requiring) career changes – compare the 666 effect of Summon Daemon for an example of the latter -, including such classics as the forbidden book, which upon reading it, requires a character to test Morale and upon failure gain Possessed as an additional talent.
But while we are at it, and because I noted yesterday how there is always room for more alternate talents:
Insanely Faithful (Preacher of Hate)
All members of the retinue are treated as if they possessed your Hatred talents.