I'm glad you asked! A Persona is a power granted to everyone who winds up here like you and I. It's what many of us use to combat those monsters, though some are more effective than others against certain enemies.

Hmm, how to put it... [She assumes a typical thinking pose.] It's like an extension of your inner self, usually in the form of some kind of mythic hero or creature. If you're in trouble, it should reveal itself to you, and give you powers and abilities to protect yourself with.

Well, hopefully. Mine didn't start out with any offensive abilities, so even after I found out about her I couldn't do much to protect myself. You can never be sure how it'll go.