One of the best reviews for SPN 4:04

Written by killabeez, read it here.

Regarding Dean's anger and the way he reacts to Sam's lies, the key for me is that Sam is not reacting to Dean's return at all the way we (or Dean) might have expected. He's nothing like all the stories people wrote over hiatus. He's not clingy, he's not overly emotional, he's not afraid to let Dean out of his sight. He's self-possessed enough to lie like a champ even in the first moments after realizing Dean's back. -- And Dean as I see him is not only scared to death of these powers of Sam's, but also deeply hurt and confused by the way Sam's acting.

Sam's depended on Dean his whole life, far more than he should, and he's struggled against that all his life, too. Now he knows the reality of being completely alone. Love like Dean's is seductive, overwhelming -- unconditional adoration, devotion, and protection is not something a lot of people are lucky enough to know