Gwyndolin soul and firelink keeper

So Me and a friend fought Gwendolin and I asked him what was the empty chest on the left side for? He said no one knows so, I joked and said I will put Gwendolin's soul in front of it and see what happens. Nothing of course but I killed the anor londo Keeper and then went to the firelink to get my estus flask reenforced and she started talking to me. saying she spoke with Frampt and was grateful for me linking the fires and being happy about dieing a human. Then she pleaded with me to do it.

Has anyone else seen this? I have read the wikis and nothing about her talking besides how she is impure and leave her alone?!?!?!?!

I always just killed her so I don't know.

She always says it after you offer up one of the lord souls to the lordvessel.