Now the important thing about Harry’s mother, the really, really significant thing, you’re going to find out in 2 parts. You’ll find out a lot more about her in Book 5, or you’ll find out something very significant about her in Book 5, then you’ll find out something incredibly important about her in Book 7. But I can’t tell you what those things are so I’m sorry, but yes, you will find out more about her because both of them are very important in what Harry ends up having to do. JKR 1999
I was thinking alound about this to Sweet Husband last night. "Is Lily even mentioned in Book 5?"
He gave me a look and said, "Um, yeah, the scene from the pensieve."
So...Lily stuck up for Snape....