One year, when they were younger, Sam broke his arm just before Halloween, so Dean gave him his old Batman costume to wear when trick-or-treating. Dean told him it would make his arm heal faster if he wore it, Sam rolled his eyes, but secretly he believed it might be true, after all Dean never lied.
This is Dean’s reaction after he kills the young man who was crazy in Family Remains. I didn’t quite get why Dean looks so upset and looks like he’s berating himself here until I remembered that this takes place mere weeks after he escapes hell. After he tortured souls for 10 years. After he tortured people. All he wanted was to save and help people in an attempted penance for what he’d done there. Killing monsters was one thing, he was saving people in the process, but here he killed a human, a boy who honestly didn’t know better than to attack. It’s such a small, barely noticeable moment but it really struck me today. The load of guilt Dean was carrying around was only growing heavier and he was buckling under the weight.