I'm obviously going to be spoiling things, but I'm going to assume you already knew that.
I would first like to start off by asking, how does one turn "Hollow"? There are many characters you meet in the game and at one point will turn into the bad guy and try to kill you. Is this ever explained why/how they do this?
My second question is, when you talk to Griggs of Vinheim about Reah, he will tell you that she is after a Flame of Kindling. I can only assume that this is talking about a Fire Keeper Soul. Does it ever explain why she's after one of these?
What happens if you kill Petrus while Reah is at the Undead Church, and never buy all her Miracles?
What happens if you leave the Fire Keeper Soul on the altar where Reah prays at?
Is it possible to offer a Fire Keeper's Soul to Reah?