Mmm. Love me some hurting woozy vulnerable Dean and some bossy fretting Sam. Dean's breaking down in tears is fabulously credible, and I quite like the bit with the wolves. This is my favourite:

Dean became aware of the shadows dancing in the little cabin, the sound of his brother’s deep breathing, the noise of the wind outside, deep and low and terrible. Sam shifted a little, threw an arm over his head, and Dean smelled him – Old Spice deodorant and sweat and blood from the hunt.

Very vivid, great sensory details, plus, cozy!