This is, like the rest of the series, unspeakably beautiful. The way Dean is so, so deeply and profoundly hurt by Sam's insistence - it's just agonizing.

Then Dean meets his eyes and it's all there for Sam to read -- fear and embarrassment and ohgod, hurt; cutting down so deep that Sam can't touch it. Yeah, Dean knows exactly what he looks like, exactly what Sam feels, and he hates it. You really keep getting the sense of beauty as a curse across and you do it so well.

he can feel the sharp point of Dean’s jaw against his mouth; has to lick a little, just to taste…
Dean flinches, tenses in his arms, and then Sam’s staring into Dean’s face, close and angry.
“What. The fuck. Are you doing?” Sam blinks at him, the outrage in Dean’s eyes breaking through the haze and he can barely answer. The way you keep emphasizing Dean's angularity is just brilliant.

“Not like this, Sam, okay? Not like -- fuck.” That Dean has to beg like this is just killing me.

Sam watches Dean’s cold mask shatter.
“So you want to stay here and party? Tie me up again? Maybe fuck me for your new friends?” OUCH.

And on the puncture wounds at the base of Dean’s neck. Oh, WOW. This ending slammed me.