@LaXnyd: Demons can have a secondary ability that's unique to each one of them, and basically those secondary abilities can be something mentally themed (perception, illusion creation, mind reading, possession, etc.)

Oh, and another thing I forgot to mention but will add to the Important Info area. Pact Bearers have a "Spirit Relic," which is the very artifact that they are given when they create a pact. It can be any kind of inanimate object (like how my character's Relic is a Pendant), and the catch about the Spirit Relics are that they're both the key to using the affinity's powers and the very thing that holds your soul inside. If it breaks, your soul is released and you automatically die, so it adds a bit of weakness there.