So, on the subject of Sam being neurodivergent…
If he often struggles to read people and agonizes over moral relativism, I think his season 8 behavior makes perfect sense in some ways…
(Especially when you add in the fight-or-flight seesaw. His wall got terribly broken and repaired; and then he lost both Dean and Cas, and he didn’t just not look for them. He was afraid of looking for them. Sam is the man most afraid of grief. Limbo was preferable to grieving them if they’d turned out to be truly dead. Thus, the resulting deserting his post / utter nervous breakdown).
Anyway, Re: Sam’s neurodivergence. Sam, and especially later-seasons Sam, doesn’t seem to operate on gut feeling as comfortably as he does by-the-book type of structures.
And while it hurts a bit to realize it, Sam could be mostly mirroring the assistance Dean and Bobby gave to him in early seasons.
After all, Sam also had a monstrous ally who earned trust and offered assistance over a period of years. An ally who even saved Dean’s life on occasion! It’s not a jump to assume Sam’s mind has created a snapshot of this instance to use in real life the way we use our experiences like a training simulation.
Post-deserting his post, Sam’s horrified by his own weakness and flakiness. So, charitably, we can assume he tries to overcorrect his support. And when he’s “looking out for his brother,” part of him is referring to this neurodivergent “checklisting of items” he’s stored in his head.
In this instance, being wary of self-interested-but-caring-outsiders was modeled by Dean and Bobby!
The Ruby scenario is now a pattern in Sam’s head, embedded like a board of blackout bingo terms.
And Sam is a little bit right in that, that no matter how “arms-length” Dean keeps his partnership, no matter how “controlling the means of communication and controlling the flow of blood donation” Dean crafts it to be, it poses real risk to Dean, which is underlined boldly in text, regardless of the stress-testing Sam engineers.
(But crucially, Sam is also a lot in the wrong, too.)
I think this “flight simulation” style of thinking happens in season 10, too.
Dean “at least Sam will die human then” Winchester and Bobby (and Cas) undertook extreme lockdown techniques to get Sam through the “withdrawal” phase of his affliction in a 4-5.
And it was successful! (Drug withdrawal is no joke, but it’s not torture for the sake of torture, or social rejection for the sake of social rejection. I personally feel like rushing to pin it as a crude stand-in for conversion therapy is uncharitable and way off.)
Point is, Sam’s got a pre-existing template for the Demon Dean purification scenario. It’s what was done to him.
His family recognized when it was “the affliction talking” to get Sam to a place of health. Sam knows Dean loves him, loves singing, loves his car…
And lo— when all is said and done, Sam is right about this. Sam’s hypocritical cruelty and evil pragmatism to save his loved ones aside, Sam is right that Dean doesn’t want to lose himself in a numbing world of black-and-white, Purgatory-style numbness and fatalism.
Dean says on multiple occasions just how much he hated becoming “that thing.” He verbalizes that the mark and demonness are an assault on his free will; and he’d rather die before becoming it again.
Of the mark, Dean calls Crowley out for lying and pulling a Metatron on Dean to further Crowley’s own goals. And of the mark, Dean says, after blacking out and losing control a la Godstiel-a-political-convection: “Fellas, this thing’s gotta go.”
Sam knows Dean, and because he knows Dean, he recognizes that the demonness was not a secret true self any more that the suicidal ideation brought on by Sam’s trials was Sam’s secret dream…
And once again, Sam’s actually a little bit right about Crowley; we just tend to politely look away from it. (Draining humans as late as season 9; killing queer suburbanites in s11 to make a hasty phone call etc etc)
That Sam is a little bit right about some details makes parsing his moral relativism even more difficult for him, I think.
(He’s also probably confused by when his emotions irrationally drive him in certain scenarios, like when he makes a connection with a “freak” that’s so strong that he overlooks “rules.” He ties himself in knots rationalizing, perhaps. We all do. It’s horrifying how irrational we are, really.)
In his middling-Sam days, when the scenario doesn’t play out according to the checklist/scenario stored in his head, Sam tries to counter-balance the equation so it’s forced to fit.
I.E: “I was wrong, so therefore Dean is also wrong because enough of these checklisted conditions look the same. No? I’ll just have to hit fast-forward on a few things and prove it to him then!”
Obviously there’s a lot more than the above at play. There’s of human emotions, baggage, pettiness, pride etc etc in the mix. But every single person’s got that, too. Being a human is complicated.
But I do think Sam’s dissociative manner of coping is nifty! The neurodivergent scarecrow/brain/head choice is fun to consider in the context of the above, no?