Dean looks so scared. He's the one who has been for years tried to keep a strong face for Sammy and everyone around him. The mark has screwed with him so much and has warped his mind that he can't even fake that everything's okay. And Sam has learned well from his big brother that even after everything from being in the pit to the trials, they will fix this. They always do. This brother bond is why I keep coming back week after week, season after season.