"Him and Castiel have just been so close for so long"

"MAY 15 SEASON FINALE | As the boys’ quest and the mytharc escalates, “There are a lot of intersecting plots and personal motivations that are going to come to a head,” teases Carver, adding that “several things will be changed forever.” Could one new mythology element introduced this season, the Men of Letters, be a part of the finale? After all, it seems Abaddon is back. Plus, Carver tells TVLine, “We will absolutely see the positive and negative effects of being legacies.” And yes, there will be “a few” cliffhangers, so prepare yourselves for a long summer."

"Any news on what Supernatural‘s Dean will be doing while Sam is dealing with the Trials? –Sue
I turned your query over to exec producer Jeremy Carver, and his response was: “I can’t say much about the Trials, but when it comes to what might be in store for Dean, I have one word: Tron."