Jesse

Dean is incredibly cruel to everyone this episode. He's trying to push them away so that they'll abandon him and let him say yes to Michael, and so he pulls absolutely no punches. He tells Bobby "you're not my father," even though he's spent the last two or three seasons calling him "the closest thing I've got to a father," because he knows how much it'll hurt. It's the same reason why he tells Sam that he doesn't believe he can resist Lucifer, and then essentially says that whatever happens Sam will end up being evil.

But what about Cas? What is the thing that will hurt Cas the most? See I think that Cas has been in love with Dean for some time now, and that Dean has kind of picked up on it. I don't think he's ever brought it up, and honestly Cas probably doesn't even know that he knows, but I think he's definitely aware of it. But when he wants to hurt Cas, that's how he does it. He takes Cas's love for him, and he mocks him with it.

But more than that, he cheapens it. You'd think that if he really wanted to hurt him, he'd mock Cas for being pathetically in love with him or something along those lines, but he doesn't. All of his allusions are entirely sexual. He reduces Cas's feeling for him to just attraction, and then he makes a joke out of it. With Sam and Bobby he was straight up mean, but with Cas he was flirty.

The real kicker here is that Dean honestly didn't need to do any of that. The easiest way to hurt Cas was just to do exactly what he was already doing: say yes to Michael and make Cas's sacrifice worthless. Cas already knows that loving Dean means pain, but saying yes to Michael? Giving into his destiny? Making Cas's rebellion mean nothing? That's something else entirely. That's the thing that leads Cas to literally beating him up in an alleyway.

This pose was a prompt on the @spnspeeddatingbang discord server, I of course had to make it Destiel. You can see the reference image behind the cut

Literally Destiel: