I'd put it in the hands of a patron known and trusted by the players. Watch them try to figure out what's happening and how to fix it. In the course of figuring things out, they'd end up in some very sticky situations, such as when their patron decides that sacrificing them to a rival is the "easiest" way out of a longer conflict or when notifying them about some danger becomes too much work.
As with Wrathbringer, I somewhat resent the mind control aspect. Corruption is so much sweeter if the mortal got to make all the wrong choices himself.
Usually, it will be sufficient to give a mortal that political acumen, let him know of the plans of the enemies, perhaps serve as a non-sentient depository of knowledge - that coupled with added charisma is usually enough to fuel pride. Once he has a few enemies, the paranoia also comes on its own.