ok here’s the thing
i think some people are taking dean’s general aprehension regarding jack as some kind of large homogenous mass of misplaced anger (often taken as “because Castiel :-(” but thats another problem for another time). Sam’s “explanations” of Dean’s feelings aid that but… it’s just sam’s words. and when you take everything into account, it falls flat and false.
In terms of interacting with jack, dean might be harsh and surely is unfiltered level of honest but he’s not mean, not cruel
where he really goes extra in terms of being rough is with sam. he is not stupid and he recognizes the difference between a toddler with too much power that should not be trusted too much because of simple damage control
and an adult man who should know better but willfully ignores every rational argument because he likes his own narrative better (sam, who dances this dance repeatedly since near day one).
He’s not personally pissed with jack, surely not as much as at the very least sam (and some people) wants everyone to think. The bar scene is textual proof that Dean can relate to Jack, the promise he gives him is only confirmation of that. Dean’s been there in a way Sam hasn’t because burdened with a power near impossible to control both Dean and Jack wanted to stop causing damage and be stopped at all costs if necessary, while sam (and cas,while we’re at it) most of all wanted to be right and win, no matter the cost (and im not just pulling old dirt out, this is recent seasons too, ie. releasing the darkness or fucking with cosmic consequences).
He’s pissed at sam’s dance no. i don’t even count at this point. He might be grieving the loss of his family but he’s not stupid. I don’t think he buys the amazing uncle sammy thing - historically there is no reason for him to and there is no reason for the audience to do that, either. And here’s why:
- sam shot dean’s biological daughter, emma, even though the situations were near identical,
- sam never gave benny minimum of trust even though benny meant so much to dean and never betrayed him
- as recently as in s12 sam sided with BMoL who were clear about their intentions to commit all monster genocide regardless of whether they preyed on humans or not.
and yet! now all so suddenly sam wants to take jack under his wings and lavishes him with sweet words, ignoring any warning signs with spectacular ease. did he change his mind after 15 minutes with jack in a cell?
or is it about the possibility to harness his power (whereas emma, benny or any other nonhuman wouldn’t be useful like that) because he can do the thing where he can open the portal to the alternate dimension where mary is? (note how he doesn’t accept her death and the texts spends time to consistently point that out)
so if you want to call someone a nasty grief-driven dick, you’re barking at the wrong tree