My theory on this one time that Dean and Castiel don’t hug upon reuniting, is Dean’s utter shame about what happened with Michael. He told Castiel it would be okay. Castiel was all, “the hell you say.” And not only was it NOT okay, it was SO MUCH LESS OKAY than even Dean was picturing.
Castiel was right. And Dean didn’t even get rid of Michael by himself. Now here he is, happy to be back with his family, but my GOD, look what he’s unleashed through his own vessel.
Frankly, knowing how Dean’s mind works, I wouldn’t feel worthy of that hug, either.
He can’t even say anything. Usually there’s a hug, and some worried anger, and then Dean or Castiel defending/apologizing for what happened and then some tried and true self-blame. Dean’s usually the first to go with that. But in that scene when he got home and came face to face with Jack and Castiel?
Not a word besides, “Cas.”
That right there reeks of Dean being so much higher on the guilt scale than we’ve seen him in years.