When Cas initiates the hug with Dean, Dean at first seems surprised and amused by it. Note the back pat, the smile, and the way he says “All right.”
Then Dean suddenly gets serious and I think it’s because it occurs to him that he has to ask Castiel to take care of Sam and not to let him do anything stupid (like following Dean into death). It’s a moment where he’s faced with his own mortality and the fact that he’s no longer going to be there to take care of his first priority: Sam.
When it comes time to actually say goodbye to Sam, they can barely look at each other. Sam’s eyes are full of tears and he’s close to losing it.
Dean grabs him and pulls him into a hug and his face is SO FULL of this fierce devotion and sadness.
Then comes the patented Dean Winchester “This hug is not intense enough- INCREASE HUG INTENSITY BY 300%” move.
[also seen in Lazarus Rising if you need another example]
And finally his expression somehow gets even SADDER (how is that possible??) and we can see the tears in his eyes as well. Poor Sam is just clinging on to his brother, burying his head in his shoulder, still trying not to completely break down.
They both seem heartbroken about having to be saying goodbye AGAIN and they’re trying so hard to communicate that without having to actually say it.
To sum up, bless this scene. It contains 100% of my daily nutritional requirement of beautiful, soul-scarring angst.
nothingidputbeforeyou 