The voice in their heads is actually the big bad of the series
In recent episodes he tries to discourage Cock from stopping the fight between Tits and Guzzler, he also tells Cock that the Game Society Pimps aren't real and encourages him to work with daedric princes. He also subtly manipulates the characters like when he told S'oggy Balls to leave the Wabbajack in a bush instead of tossing it in the water.- Furthermore the Grand Finale will reveal more about this.
- Partially confirmed as of the premiere of season 7.
