#tbh every introspection i do is never an absolute full-fledged interpretation more like i entertain ideas/possibilities that might line up

[shadystranger]

Dean's outbursts and occasional mistreatment of Sam in the later seasons stem from his new-rooted certainty that Sam will never leave him no matter what anyway. But, when someone else mistreats Sam, Dean's response is immediate and protective. He becomes exceptionally attentive and caring, almost to an exaggerated extent, ensuring Sam's well-being. The presence of a primary abusive figure triggers Dean's reverting to his role as Sam's primary protector, performing his role with such exceptional dedication tailored to Sam that it borders on too perfect like a high. And Sam considering his history he doesn't work too well resisting temptation and these intervals of extreme high even if in the long run there'll be downs that are outright harmful to him. That catalystic payoff diminishes everything else in Sam's possibly tunnel visioned rationalizing of things. Especially when it comes to Dean because that's when his call is mostly distorted.

This cold-and-extreme-hot, robe-pull that Dean performs with Sam intentionally or not. Both Sam and Dean are acutely aware that Dean is uniquely positioned to affect Sam profoundly; he possesses the singular ability to bring Sam down to his lowest points, while simultaneously being the only one who can elevate him to his highest peaks. This dynamic solidifies Sam's belief that no one will ever treat/know him so good to 'him' as Dean does. And Sam who never resisted his addictions just loses himself completely in it and chases it the duration of his life.

Sam cements the notion that his safety and happiness are inextricably linked to Dean.