Supernatural (TV series)/Recap/S04/E20 The Rapture

Season 4, Episode 20:

The Rapture
Castiel tries to give Dean an important message in a dream, but when the boys arrive to speak with him personally they discover instead his vessel, Jimmy Novak of Pontiac, Illinois. Castiel's been recalled to Heaven for something, but Jimmy doesn't know what and just wants to go back to his wife and daughter. But the forces of Hell are after him as a former angelic vessel.

Tropes

 * Does This Remind You of Anything: Sam's addiction to demon blood is basically the supernatural equivalent of a heroine addiction
 * Downer Ending
 * Grand Theft Me -- They need permission, but this is basically what angels do to their vessels
 * Little Miss Badass -- when Castiel is in the body of a young girl