With the Darkness unleashed, Dean and Sam set out to try to find the Darkness, but are shaken to learn that the entity they are hunting is essentially God's sister, who was 'sacrificed' so that he could create the world. Manifesting as a woman who comes to call herself Amara, Dean finds himself unable to kill her due to a twisted attraction, but matters become even more complicated when Castiel consents to act the vessel for Lucifer when he becomes convinced that only an archangel has any chance against Amara. This strategy fails- speculated to be due to Lucifer's status as a fallen archangel- but the Winchesters are eventually contacted by the true God, now revealed to be Chuck Surely, the author who wrote the Winchester Gospels, who is able to make peace with Amara and depart.