Kitty Rocks the House strongly implies that Roman, the Big Bad so far, has a hidden master himself. A supernatural bounty hunter that Amelia calls a Fallen Angel says that she works for the same being as Roman. She also calls Kitty, Rick, and Father Columban alike traitors. The thing they have in common is that they're all Friendly Neighborhood Monsters. Clearly, Roman's Caesar is the Devil himself, or as close to it as mere mortals can understand.