Have you just tried asking her? Seriously. Write down a couple of questions - start vague (what's your fav song/book/method of killing or whatever) and then get a bit more personal (what do think of the protagonist? have you met the antagonist in an earlier part of your life? do you see yourself staying a minor character?). It's frightening how talkative some of them get - although thinking about it, everyone likes talking about themselves, why not minor characters too?
One of my throw-away characters (not even minor) is now vying for main character position.*

*See? Talking about myself now.... Good luck