Changes

Dean is working with Castiel to search for Sam in [[12.02 Mamma Mia]], and struggles with the return of his mother Mary. She overhears his conversation with Cas, and Dean tells her he's glad she's back but feels she needs time to adjust. Mary worries that Sam won't be able to forgive her for her deal with [[Azazel]]. Cas calls with a possible location for Sam and texts Dean the address. Mary insists on coming along and Dean argues against it, but loses and Mary joins him. In the car, Mary tells Dean about her time as a hunter, how she was good at it but also realized that all hunters end up dead. Dean tells her about how she died, how it caused John to become obsessed with hunting and raise him and Sam in the life, and how Sam wanted out, but when John went missing, they realized they only had each other. They arrive at the house and join Cas, and while searching the grounds Dean comes across a sigil and disappears. He reappears inside the house where Toni catches him and shoves him into the basement with Sam and threatens to torture him so that Sam will give up information on the American hunters. Mary appears and threatens Toni with a gun, tossing handcuff keys to Dean who releases himself and Sam. Mary and Toni fight but are interrupted by [[Mick Davies]], who apologizes for her behavior and states that the British Men of Letters want to work with them instead.

In [[12.04 American Nightmare]] Dean, still upset about [[Mary]]'s departure, travels to Mason City, Iowa with [[Sam]] to investigate a person who died while being flayed by an invisible force and displaying signs of stigmata. As they discuss the victim, Olivia, with the priest who witnessed her death, Sam notices Dean is very short with him. They wonder if perhaps it was caused by a rogue angel, so Dean calls [[Cas]] to discuss the case. After hanging up with Cas, Dean texts Mary to check in on her and asks if he should still call her Mom. Sam returns and Dean briefs him on Cas' news - the gates of Heaven are still closed, so it can't be an angel, and that he and [[Crowley]] have teamed up to hunt for Lucifer, who has possessed the "Master of Butt-rock" [[Vince Vincente]], and teases Sam when defends Vince. They head to the morgue to examine Olivia's body where Dean is dismissive to the ME, and Sam calls him out for being cranky which Dean dismisses. Next they question Olivia's former employee and replacement, Beth, who's also a Wiccan. Dean believes she is responsible but Sam disagrees. A grocery delivery guy is killed in the same fashion, and Olivia's case files show a connection to the Petersons, a "real Old-Testament type" family. They question the family, and afterwards Sam once again questions Dean about Mary's departure and how he's dealing with it, which Dean again brushes off. Discussing the case, Sam believes their dead daughter, Magda's, ghost is responsible. Dean disagrees, believing Beth is the killer, and leaves to track her down leaving Sam at the farm. Dean questions Beth and determines she was not responsible for Olivia's death when he recieves a phone call from Sam, who tells him Magda was still alive before being attacked and disconnecting. Dean rushes back to the farm in time to save Sam, who was about to be poisoned by the Petersons. Afterwards, Dean receives a text from Mary where she apologizes for not getting back to him sooner, and says that she will *always* be "Mom".