one of the things you have to understand about dean and jack is, post-tombstone at least, their dynamic kind of seesaws between “I was wrong about you and i want to continue being wrong now that i really know you” on dean’s end (14x07 establishes that he’s literally never forgiven himself for mistreating jack), and then on jack’s end it’s like “I want you to be wrong about me too.” they’re on the same page when it comes to the topic of jack possibly maybe being evil—and in a weird way, they almost always have been ..? and not even just them. it’s a basis for so much of jack’s other relationships - and how can it not be when your two families are a particularly preordained set of hunters and the cosmic forces that they were preordained as vessels for?
in 13x02 when dean walks in on jack stabbing his chest repeatedly, he’s rightly horrified, and this entire situation is because of jack ‘recreating’ his own horrifying moment where miriam stabbed him and nothing happened. to put it shortly, they’re both horrified at the sheer unknown that is jack and his powers. jack says “i can’t control whatever this is. i will hurt someone.” not a threat, but an acknowledgment that he is both dangerous and doesn’t fully understand what he is. then, he says “if you’re right…” and trails off. they both know what it means for dean to be right in the scenario, and he says just that (probably harsher than he should, but) for all intents and purposes, he will take the responsibility of killing jack *if it ever comes to that.* (read: IF ITS ABSOLUTELY NECESSARY. He Was Not Just Threatening Jack I Promise).
and then there’s everything else that follows. after jack’s first Ever kill in tombstone he says, maybe dean is right, and of course by now dean knows that he isn’t so he says “if you’re a monster [for one mistake] then so are we [for our mistakes].” and dean isn’t the only person to be distrustful and proven wrong—when they call rowena in to help jack’s 'condition' she very bluntly tells sam that, from what she knows of Lucifer, the world would be better off without his son. and what does Jack say? “you might be right.” jack knows very well what the other end of the scale is. the fandom has a tendency to oversimplify a lot of things, often making them static or one dimensional to fit a certain idea. in this case it’s both jack and his dynamics with other people (especially dean, but everybody else counts as well).
even when he’s not being seen as an infantile stage prop, jack still isn’t given much interiority for thought. he’s almost portrayed as blissfully unaware of basically everything, including his status and what it means to others. but the fact is, he knows. after his first kill and unfortunate meet with his father, he knows. maybe jack doesn’t know everything about lucifer’s connections to his immediate circle — ie, does he know that Lucifer burnt rowena alive? left a charred, anguished corpse behind for her to grow back from? that that’s why she was ready to let him die? — but he still understands enough that he doesn’t fault people for feeling certain ways about him; “We’re still trying to figure that out, but I’m trying not to be like him.” I’m probably losing my train of thought but now that I think about it, it’s very interesting to me that jack would say ‘I’m trying not to be like him.” Like, not just ‘I promise I’m not like him.’ Nothing definite, because Jack doesn’t know that he isn’t like Lucifer yet, and he’s plenty of moments to show that he holds a few similarities at best.
but that gets back to my point. this whole ‘will he, won’t he” thing is pretty much the basis of jacks whole character/person, including the dynamics he forms with other characters, and he is extremely aware of it at all times. he’s not a helpless victim of random bullying. the very reason he acts the way he does is specifically because of the fact that he holds so much potential as a threat, and actively works against it.
when jack is dying, dean can’t stand to be in the same room as him. after nearly two years of officiating jack as their family, he still hasn’t forgiven himself for his mistreatment, and now he thinks he’ll never have a chance to really make things right. when they’re fishing, jack says he’d miss having more time with dean, and dean says “who knew hanging out with me [of all people] would make you sentimental.” it’s very clear that dean doesn’t think he deserves this kind of connection or high value from somebody he treated so poorly over something he was wrong about. and I don’t think it’s by chance that this episode is flashed through deans head in the graveyard during 14x20, because what does jack say while he waits patiently to die? “You were right all along.”
It’s soul-crushing. The fact that it still hangs over their heads two years later after making peace with it, and it will continue hanging over their heads after they make peace again. The fact of the matter is, Dean does not want to be right anymore. He was proved wrong and he was grateful to be wrong, because he does indeed love Jack as a son and a friend. Likewise, Jack loves dean as both a friend and father figure, he loves sam and Cas, he regards all of them as his true/chosen family. He doesn’t want Dean to be right either. So much of the things his hallucinations mock the attachment he has to his family and home and the role he wants to upkeep within it, and how he cannot have it anymore because of Mary’s death; or, because Dean was right, and he is the monster they always thought he was. All the guilt and attachment he feels is “just a sneeze,” and this is who he really is.
It’s tragic, but it’s one of those things that I feel does not get recognized enough. Dean and Jack (and everybody else) are on way more equal footing than is credited to either of them
