In the first Dark Souls, when you enter Quelaag's Domain she attacks you without any discussion or trying to know why you have entered there.
Her sister, however, shows no hostility and neither does her servant, even though you killed Quelaag.
So why would Quelaag be hostile at first sight, and doesn't try to know if you came there to help her sister and give her humanity? Does she have any reason to attack the player instantly?
Any item lore or suggestions are appreciated.