Oh, the desperation in Harry's slack mouth, the tactile stickiness of the come dripping across his cheek and chest... and the dreadful ambiguity in Severus' hand, just caressing Harry's back-pulled elbow like he is. One hardly knows whether to think the words gathering behind those teeth are of comfort, or triumphant derision. Either way, it's clear he's enraptured.
Beautiful. Just beautiful. I wish I could make light dance like this...