The Shield of Angels

Castiel was doing good, he had a stable job, which was incredibly good for a 19 year old, just got out of a relationship that was toxic and slightly abusive, and was able to get him and his sister a trip to Haiti for vacation.

Now, (after his death) he's gone on a quest through all the different stages of the afterlife to deem himself worthy of going to heaven and not spending rest of eternity fighting for his life in a version of purgatory he has never heard of, the land no one has been able to get out of no matter how hard you try.