I was reading s-cornelius’ comment on deangirl’s post on how Sam knows about Dean and Cas, and I just couldn’t stop watching this gif.
It’s Sam’s body language that makes me absolutely sure that he’s figured out what Dean and Cas haven’t–that they’re in love. Because we’ve all seen this kind of body language in tv shows and movies over and over and over, and we’ve seen it in specific circumstances.
This isn’t Sam giving a sitrep about a tactical problem. This is Sammy bracing himself to give his already debilitated brother news he believes might break him.
And I mean literally bracing himself–look at the way he takes a breath and shifts his weight before he speaks. The way he licks his lips after he says, “Listen, Dean,” delaying just a fraction of a second before he tells Dean that Metatron has Cas. Watch how he keeps his facial expression calm and forms the words very carefully, speaking a little slower than he usually does, so that Dean, who’s really still a bit out of it, can clearly see as well as hear what he’s saying.
This is the demeanor of a person saying, “I’m sorry, we’ve done all we can, but you should prepare yourself for the worst,” to someone who may be about to lose the man he loves.