Dean internalizes. When he's at his most hurt, most terrified, he shuts down and emotionally turns inward. He'll still lash out in anger (like when he yelled at Bobby to just let the world end, that he didn't care anymore, once Sam was dead), but it's different.
While Sam and John act outwards. And they turn off those emotions as much as they can.
The problem with the two of them was probably always that they were just too much alike. Neither deals well with compromise or with not getting what they want.
Those Winchester men are complicated.
And I love how neither brother is really, deep-down, what they seem at first sight.
__________________
"Don't be afraid of the dark? What, are you kidding me?
Of course you should be afraid of the dark.
You know what's out there." --- Dean Winchester, Supernatural
icon by lunas_borednow