All Dean has ever wanted is the one thing he just can’t have: a family of his own. And while so many things have stood in his way, it boils down to the fact that he believes people would be better off without him. It’s not hard to see why. When Dean is caught stealing, John can’t even be bothered to come pick him up, he’d rather have him “rot in jail.” So yeah, of course Dean thinks he doesn’t matter, can’t see his own worth. But just look! Dean, can’t you see how perfect you are for this job? He always knows just what to say, because he remembers when he was young. Remembers the things he wished John would say, on days when he wanted nothing more than for his father to look him in the eye. But he can’t fold, can’t indulge, because he’s afraid of what he has the potential to become. Please Dean, can’t you see? That’s not you. You’re a better man than your daddy ever was, Dean Winchester.
And Dean always squats down when he’s talking to kids, gets on their level. It takes the whole “adults looking down on you” dynamic away and just leaves a grown man bringing himself down to look them straight in the eyes. Because he remembers what it felt like to be looked down on, in many ways still knows what it feels like to be looked down on, whether he’s actually being looked down on or just imagining it. Because Dean Winchester has never felt worthy of anything or anybody. That’s why he always makes excuses for John and for Sam and for Cas. Why he always runs back to them. Why he’ll never stop defending them. Because no matter what they do, it can’t be as bad as how he thinks of himself.