I also have limited scope; I am now Voldemort's personal potioneer. The loss of most of his soul has had a curious effect. The remaining fragment still inside his corporeal body seem reluctant to stay there. He requires a particular potion once a day to ensure it doesn't flee from his body to latch onto another, and it is a particularly challenging thing to make. I spend most of my days creating it. I considered tampering with the potion, but it is in our best interests that he takes it. He would identify a poison immediately, and if I brewed the concoction incorrectly, we would essentially have a soulless Voldemort, still with his full power and a second Quirell situation.