Oversight
You like the fact that he's rough with himself. You enjoy his discomfort. He closes his eyes in the dark, stone-faced, flinching in climax, one wordless evanesco and immediately asleep. Takes a potion if he lies awake too long. His free hours are in solitude, and he shows them to you openly, proud when he is unhindered by others. Grading and brewing, devoted to productivity.
His superiority is tempered with shame as deep as identity. He longs for contact, but every real connection is at a distance, and the protective gap is also the harmful void. A knowing glance from McGonagall at breakfast, a kind word from Dumbledore in the corridor. He saves these, holds them close, revisits them into meaninglessness. It's a habit that he can't quite break. Vestigial loyalty to the powerful. He shows you these slips because he is sorry for them. You are all he needs, and his admissions tell you so.
You know it's pathetic, what he does with himself, and you savor the thought of him alone in a room, behind a locked door, feeling watched, unable to stop seeing himself in third person, always pinned like an insect to be examined, displayed. You see him fail to relax, and you smile. Feeling foolish, he speaks over his shoulder to an empty chair in hopes that you will hear it later, a small bookmark in the ledger of existence his mind makes for you. You observe him outside a circle of people, committing himself to indifference. His posture is poetry when he's walking into a room of hostiles. It's admirable the way he holds himself up to be seen in silhouette, always a moment from leaving.
You mentor him with the barest scraps of praise, and admire the changes your touch creates. He is damaged, but sturdy. He upholds you as a fallen frame: repurposed, foundational. There's seldom a need to make him kneel anymore, because his back is as straight as a column, and he meets your eye not out of defiance, but submission, spreading his mind before your scrutiny.
There are none like him, and his rarity makes him so useful that you very nearly love him. The remembered rooms in his mind become a comfortable meditation for you. You are closest to regret when you consider the day he will not be useful anymore. You will, as a mercy, never turn your wand on him. You know he will appreciate the gesture, as one final praise. Let him at least die fulfilled.