on season 8
After Sam and Dean investigate a series of abductions, a weakened Castiel appears to them with no memory of how he escaped Purgatory and he asked about bella and grace they are save back at the save at the safehouse . The abductions turn out to be known future prophets, as only one prophet can exist at a time, meaning that one of them will become the new prophet if Kevin dies. Dean has flashbacks of his escape from Purgatory and deals with his guilt for not saving Castiel. Kevin is tortured by Crowley into translating the tablet and reveals to Crowley that there are more tablets. Sam, Dean, and Castiel intervene and save Kevin from Crowley. Castiel breaks the tablet in two pieces and Crowley flees, taking one half of the tablet with him. Kevin and the remaining prophets are rescued. Castiel reveals that he chose not to leave Purgatory with Dean and bella, telling Dean that remaining in Purgatory was his penance for his previous actions castiel went to see bella once again she is shock to see him okay and he explain everything afther the last time he saw and a 3 year old grace comes in the livingroom she is happy to see her daddy and castiel apologize that he missied another bd and make up to to spend the day with her and mommy as they spending the day togther Castiel all of a sudden finds himself in a mostly white room standing in front of a woman at a desk. He asks her where he is, and she says that he's in a part of Heaven not many have seen. She introduces herself asNaomiand tells Castiel that he was rescued from Purgatory by angels so that he could help Sam Dean bella and his daughter and report to her about their activities. Castiel refuses to spy on the Winchesters, but is unable to resist telling her what she wants to know when she asks him. She also tells him that he won't remember their conversations and that no one, including himself, will notice that he's been gone. In the next instant, he is back standing with Sam and Dean, agreeing to help them look for the other half of the Demon tablet that Crowley holds as bella shows up with grace she went to castiel and ask what happend and why he keep disappearing and he tell her later