"But you're hungry, right? You need this." Dean's desperately scrambling to get Cas back into bed with him, and there are so many things to blame that on -- the incubus bit, the arrow -- but the warmth he feels deep down, way down deep underneath all the outside crap? That's Dean. Everything else is just amplifying it and letting him ask for it in a way he never, ever would be able to in real life, like... ever. That's where the desperation is coming from, but it's hard for him to accept that, so he pushes past it.

"And Raphael hit me with a dumb arrow. Feels like I can't breathe when you're not touching me." See? Dean needs this too. Life and death reasons (he won't die from the arrow, though he doesn't know that), which are the best kind of reasons because there's no room for saying no, no room for feelings to get in the way.