Severus waves a no, I'm all right hand at him, and, when he can, shoots a look of loathing at the teacup, which obligingly boils, bubbles rising to the surface merrily. "If an unfortunate throat could stop me from talking too much for my own well-being," he says, straight-faced except for the eyes, "the habit would have been beaten out of me long before I stood my OWLS."
"I know," he gripes. "Which may actually, incidentally, be primarily your doing. If you hadn't set that blasted troll loose, the Weasley boy would never have let that confounded girl within fifty yards of the brat."
He passes Q some tea to stop him rubbing his forehead. "I thought not. I really have no notion of your normal competency level in Occlumency, but defying him to his face, straightforwardly or otherwise, is difficult enough when well-trained at it and not in possession of the same nervous system. Furthermore, Potter escaped with a few cuts and bruises, a ripped jumper, the adulation of the entire wizarding world, the loyalty, admiration, and companionship of his chosen--one of whom, as you point out, would have appeared to her best advantage in Ravenclaw--a core understanding of his enemy's nature, the House Cup, no sense of condemnation at all for having taken a life, and a basket of sweets. So why should you feel guilty?"
"That's rubbish," he says irritably, feeling instinctively that that sort of talk needs to be nipped in the bud. "If you hadn't been any good, you wouldn't have been re-hired. Relative stability in a post that hadn't had any in years wouldn't have been worth both the risk of your life and a second year of poor performance. The Headmaster may have preferred a certain ruthlessless and benevolence in his administrative style, but he was above all a pragmatist. Students who took their NEWTS and OWLS in your years performed adequately--which is to say, poorly in comparison to students who had the same teacher every year, but well in comparison to Hogwarts students of other years--and while you taught, the Slytherins at least performed well on Saturday evenings."
"It was a good chance," he protests, congenitally incapable of taking a compliment. "It would have been the most personal, intimate method of killing me at his disposal, and presuming that the smokescreens worked as intented he would have wanted to make very sure of defea--" The word seems to echo in his head, even before he's finished it, ringing, draining his blood far away from him, into the floor, even his irises feeling whitened, falling away, like shining white hair falling through the night in a burst of wrenching, nauseating green. The world cycles in hummingbird-wing beats through feverish, absolute zero, again and again, and his teacup explodes in his hand into a thousand shards of white porcelain and milky-brown ice. His frozen lips mouth, albus.