Supernatural (TV Series)

At the end of Season 6, Castiel (after lying to the boys about teaming up with Crowley, The King of Hell, to find how to open the door to Purgatory) absorbs all of the souls from Purgatory and becomes a god. Since "God" hasn't been around for years (and is hanging out on earth somewhere, refusing to get involved anymore), Cass takes over running Heaven.

Castiel becomes a vengeful God, killing thousands of angels who sided against him in his war against Raphael. He also starts killing false prophets, hypocrite preachers, KKK members and, basically bad people. He does do nice things as well, like heal the sick and the blind who are good people. During this time he and Dean are not talking. Castiel was angry that they didn't believe in him, but let them live because he said killing them was pointless - but he also refuses to help Sam. The wall Death installed in his mind to block all memory of being tortured by Lucifer and Michael i their cage in hell, was crumbling and it was driving him insane. Castiel had promised to help Sam, but because the boys didn't support him, he refused, knowing it would eventually kill Sam.

When he starts losing control and massacring people, Sam and Dean try to get Death to kill Castiel, but he refuses. Eventually Castiel realizes he can't control the monsters inside of him (Purgatory is where demons, vampires and monsters go after they die), and asks Sam and Dean for help. He knows he's dying, the monsters are tearing his vessel apart.

Dean, Bobby and Sam help Castiel reopen the portal. Cass releases all of the souls back into Purgatory, but once the portal is closed, he realizes that the worst monsters of all - Leviathans - hung on and he was too weak to stop them. They kill Castiel, and knowing his vessel will explode , they walk his body into a reservoir, where he explodes under water.

15 episodes later we find out that about one month after that happened, Castiel was resurrected (God is the only one that can resurrect Angels, so this implies that he's still watching and only interfering when he wants to). Castiel's resurrection has left him without memory of his past deeds, what seems to be a coping device as he was a brutal god. Not knowing what he is, a woman finds him (right after he walked out of the water, naked) and marries him(?!) thinking he is a faith healer because he can heel people by touch.

Dean, not knowing this faith healer is Cas, seeks him out as Sam is completely insane, with only moments of lucidity - and his body is dying from lack of sleep. Meg finds out about Cas and tags along. Shortly thereafter Cas is reminded that he's an angel and his memories (and the pain that goes with them) return. He tries to save Sam and rebuild the wall in his mind, but he can't, so he sacrifices his own mental health and takes all of the pain and fear associated with Sam's time in hell, and takes it on as his own. No more hallucinations for Sam, but Castiel becomes comatose.

When he revives, a few episodes later, it is as if he had a nervous breakdown. Cass can't take stress, doesn't like confrontation and refuses to help Sam and Dean smite the Leviathans. Eventually, because Dean stops being angry with him for waiting so long to help Sam and bringing the Leviathans into the world in the first place, Cass agrees to help them take out Dick Roman, the leader of the Leviathans. When the kill Dick, he explodes and once the shockwave and goo that's left settle, Dean and Castiel have disappeared. They ended up being to close to Dick when he exploded and went to Purgatory with him (although we never see him again).

And THAT is Castiel storyline in Season 7.