I will jump in while Sabrina gets some much-deserved rest.
The contract was, ah, verbal? I didn't know how to read or write back in those days, so it would've been useless to draw it up on paper. If it can be made physical now, I don't know. I think that may be one of the ideas being considered.
There's just a few minutes before midnight, but I'll ask anyway: what would a purification spell entail? As I said, I don't mind a little pain, I just don't want to, ah, trip any wires, so to speak. If the other party to the contract knows what I'm trying to do before it's done, I can't imagine he'll be pleased.