Happiness
I noticed in both episode 8 and 9 that happiness seems to be a key term.
In Episode 8, we see the Empty telling Cas that it won’t take him until he gives himself permission to be happy. Now in last night’s episode, when Dean and Cas were talking at the recycling facility, Cas comments on how happy Dean is even with a broken tape deck and all. Then, when Dean talks about his experience with Michael, Dean says, “I won’t be truly happy until he is dead, and I kill him.”
Then, by the end of the episode, right when Dean finally has the chance to kill Michael, right when he has his chance to be happy, Michael takes over Dean’s body again, depriving Dean of one of his happiest moments. Michael said his strategy to wait for that moment is to keep Dean quiet while Michael was possessing his body.
See where I’m going with this?
Like Dean, once Cas allows himself to be happy, once he is at his happiest moment, the Empty will take away that happiness and make him miserable.
It will make him quiet.
The Empty hates Cas and much rather prefers taking him over Jack because Cas was the one who woke up the Empty in the first place. So, by taking Cas when he is truly at his happiness, like Dean now, he would be miserable and submissive to the higher being who will keep him prisoner and keep quiet in the Empty.
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Other parallels:
Michael left Dean’s body because Dean wouldn’t stop resisting. He was annoying Michael. The Empty brought Cas back because Cas wouldn’t stop resisting. He was annoying the Empty.
I don’t think this was intentional, but let’s pretend it was. Dean and Cas’ outfits were matching with both of them sporting a beige-ish/tan jacket/coat. Maybe it was a way to put something physical to represent their two paralleling storylines and their relationship with more powerful and higher beings???
¯\_(ツ)_/¯












