In the first half of the ninth season, the angels have fallen to Earth and two angel factions are warring against each other while hunting Castiel. Rogue angels roam the Earth causing trouble. Castiel is now human and has to adjust to his new life while Crowley is held prisoner by Sam and Dean who are trying to use an old blood ritual to turn demon Crowley back into a human. Sam is left near-death from the Trials of God and Dean is forced to let an angel, claiming to be Ezekiel, possess Sam to heal him from the inside. Dean must hide Ezekiel's presence from Sam so that he won't expel him and die while also keeping Castiel away at Ezekiel's demand. The brothers search for a way to return the angels to Heaven. Eventually it is revealed that Ezekiel is actually Gadreel, the angel who let Lucifer into the Garden of Eden. Gadreel murders Kevin Tran and escapes to join Metatron, while Castiel regains his powers after taking the Grace from another renegade angel. With Crowley's help, Sam expels Gadreel, but the experience causes Sam and Dean to split up while letting Crowley go as part of the deal Dean made for him to save Sam.