The demon scam

For some reason you decide that you can trust this demon with the truth. "Well, actually..." you start with a little frown, "I and my sister came here from the mortal world by accident."

The demon flinches and stares at you as if she doesn't belive what you're saying. "You're a MORTAL..!?"

(What letter do you have? The most resent ones are the ones that should be concidered valid.)