Ooooh my god, I'm on season 9 of my SPN rewatch (about halfway through) and something finally makes sense to me this time around.
Sam is going through his teenage rebellion phase!
You're probably thinking "but Zaira, he already had that when he was an actual teenager"!
Yes but that was rebelling against his biological father. But now he's finally able to rebel against his actual parent.
And why is this? Because the trials catapulted them both back into their parent-child relationship. Because from the second that Dean picks up on the fact that the trials are making Sam sick, Dean slides into parent mode. He starts to make decisions pre-emptively to keep Sam safe and relaxed when a caretaker!sibling would ask if the injured sibling would ask if they're good to keep working. He prepares and brings food/drink to Sam repeatedly when a sibling would ask if the injured sibling wants something to eat or drink. At this point, sibling!Dean has gone dormant and parentified!Dean has reawakened.
Because Dean has reverted to this programming, he has reverted to the desperate need to do anything to keep his child alive, even if the child hates him. A mindset that parents are trapped in.
The first sibling thought that Dean has had is to leave to give them both distance to recover and give Sam space.
Where Dean is acting like a parent, Sam is acting like his child.
It is completely reasonable for Sam to be upset over how Dean saved him and to keep making decisions for him. But it's how he's going about being angry at Dean is rather childlike or teenager like. Not childish, but childlike.
He's moody and hurt when Dean leaves even though Dean explains it to give Sam space. A few episodes later, they're working on a case and Dean tries to do it by himself so Sam can be comfortable but Sam gets upset at Dean for abandoning him. Dean finally caves and admits he wants to be near Sam. Sam says he wants that but also states that they're not brothers anymore right now.
This setup is why I'm saying that Sam is acting a bit in a childlike manner. Because even though he's rebelling against Dean and pushing away him away (which is reasonable) but also needs Dean to be near him (abused children can have a confusing, clingy relationship with their parent even if fighting). Sam wants him close (physical proximity and possibly emotionally) but also keeps throwing up barriers that Dean doesn't know how to navigate.
He wants Dean to talk honestly with him (which Dean tries to be) nd see reason but then when Sam explains himself he's still being vague in his answers. Saying things that are honest but also worded in a way that will purposely cut at Dean's soul. When if Sam added more detail to responses, Dean would still be hurt but understand more clearly. Dean has a lot of insecurities and anxieties, he has an incredibly brittle core, he needs deeper details in order to get an actual picture of what Sam is feeling.
Like when they're in the kitchen, Dean tells Sam that he'd do anything to get Sam out of a coma. He says that Sam would do the same. Sam's like "no, I wouldn't." Dean is visibly injured by these words as Sam leaves. This answer feels petty and childish because he obviously wants to injure Dean, to lash out in retaliation.
A more mature way (which sam usually is) of saying this , is to explain why he would let Dean pass away. He could have said something like "because you deserve to rest", "Because it's cruel to force you to keep going", "Because you've already done so much for everyone", etc. Anything to explain why he would let it happen so that Dean isn't left feeling gutted.
What I'm trying to say is that this season, both Sam and Dean are emotionally injured. That injury has regressed them to the default setting John programmed them to be: Parent and Child.
This programming makes it nearly impossible for them to find their footing as equal brothers because they're instinctively finding themselves in the power-imbalance of a parent-child relationship.
So, again, John fucked their lives.











