Okay so I was rewatching the spn s6 episode “You can’t handle the truth”, and let me tell you something, Dean beating Sam to unconsciousness is fucking brutal.
The act on its own from a 3rd person POV is horrible enough to make me irrationally angry, but if we see it from Dean’s POV is even more horrifying.
So Dean doesn’t know Sam is soulless, for him Sam could be messed up after hell, this could be a way to cope or something could’ve happened or changed in him after being in the cage with Satan and Michael, which surely qualifies as a traumatic experience, hell, Dean has been to hell already and he admitted his hell in comparison to Sam’s was gonna look like a walk in the park, and he came back messed up, Sam offered him his support and listened to him when he needed to be talk, he comforted Dean, he was there for his brother, so now Dean thinks Sam is messed up after hell, that his head is all over the place, and when Sam admits he feels something’s wrong with him and asks Dean for help, what does Dean do? Beats Sam until he’s bleeding and unconscious on the floor.
For all Dean knows, Sam unknown mental state could’ve worsened, and he didn’t give a crap, he didn’t know what to do with Sam so once again he punched him out of frustration.
Some of you may say “oh but Dean was angry because Sam let him get turned” yeah okay, Sam literally admitted it was because he couldn’t feel a damn thing and that he thought hell messed him up which according to Dean’s knowledge, could be entirely plausible, who knows what Sam could have returned like? If he’s asking for help, beating Sam, who’s already suspected of being mentally fragile, is not the answer.
Also an overload of frustration because you can’t understand something is no excuse for beating someone to unconsciousness, nothing really is an excuse for it, except for self defence and Dean was not defending himself, he was hurting Sam.
Note: excuse my possible grammar mistakes, English is not my first language.