Snape had felt almost at home in Azkaban, for without the Dementors, it was just another dungeon. One damp stone wall was much like the next. The filth and mindnumbing boredom he could have done without, but at least he did not succumb to the madness of claustrophobia and sensory deprivation, as so many had. In addition, within the first two years of his interment, someone Outside had bequeathed the prison with a lovely library, and indeed, many of Snape's own books turned up, confiscated from his office and Spinner's End. He learned years later that the library was conceived by Hermione Granger as part of her meddlesome "reformation" of Wizard society. The news was enough to make him boycott reading for almost six months, until unrelenting boredom forced his hand.
But now he was at home, in Hogwarts. Stone walls, fifty years of new books to peruse in the library, and the freedom to walk about utterly alone. The grounds became his sole province at night, when the students were ensconced in the castle and no one could bother him as he took in the clean, cool air and moonlight. Snape virtually stopped giving detentions, as he wanted no truck with bothersome students taking up his quiet evenings.
He had a rather unpleasant shock one unseasonably warm October evening when he literally ran into someone during his stroll. Snape barely had time to register the collision when the other shouted, "OFF!"
"Patience, idiot! Who goes there, and what are you doing out on the grounds at night?" he growled as he regained his balance. The moon had not yet risen and he still could not see whom he had struck. Memories of Potter and that Invisibility Cloak came rushing back to him.
"I'm Pendragon, you fool! Why don't you watch where you're going!"
"As if I can help the fact that you are dressed as dark as the night itself!" He felt uncomfortably foolish, having mistaken her for a truant student.
"Oh really? Pot, meet Kettle! Though I observed you coming long ago. Your vision must be deteriorating, old man."
Snape's jaw fell. Not only was she being insolent, but she was right, damn her; he could hear that she was directly in front of him but he still couldn't see a thing. No, it wasn't that dark--he could see the white marble of Dumbledore's tomb a few paces beyond. She was playing some sort of trick on him, and Snape was infuriated. He reached toward her voice with his hand and came into contact with her forehead immediately. Impossible! He was practically standing on her and still couldn't see her.
"You are spelled for invisibility, are you not, Pendragon?" he snarled, patting the top of her head in search of a cloak.
She gripped his arm in her remaining hand, which was unexpectedly strong. "I am not! Stop groping me! Do you mean to say you can't see me?"
"Believe me, if I could see you, Pendragon, I most certainly would not be attempting to grope you."
He heard her breath catch in her throat just before she flung his arm away. A thin smile spread over his lips. Easy as shooting fish in a barrel. "Even I am not so desperate."
He knew he should be able to see something; he had not felt the telltale chill of a Disillusionment Charm when he touched her. He could hear her footfalls as she ran off over the lawn, but he couldn't even see her silhouette against the lights of the castle. It was very strange and disconcerting; this was a form of magic he had never seen before.
He told himself that the tiny pang of regret in his chest was his disappointment at being unable to witness the painful impact of his words.
Snape expected some sort of retributive comment at breakfast the next morning, but none came. Pendragon didn't vary from her regular routine. She ate dry toast with her left hand, drank her pumpkin juice in one draught, and stomped out of the Great Hall as students cleared a path before her. Snape realized that he could not tell whether she deliberately avoided his gaze, because she had never once looked up from the table during a meal in all the weeks he'd known her. It occurred to him that perhaps she took her toast dry because she was unable to butter it one-handed. He sneered at himself for his sentimentality.
Potter leaned over the table and caught McGonagall's eye. Though they did little more than nod at one another, Snape found himself inordinately frustrated by this exchange taking place before him. "Secrets, Potter?" he growled.
"Nothing that would interest you."
Potter peered at him, his gaze intensified by his fractured eye. Snape wondered if he could actually see with it, and was glad to have the distraction until Potter dropped his gaze to the tabletop and spoke. "It's Pendragon. She seems worse today."
"What do you mean? She behaved exactly the same as any other day. Worse in what way?"
Potter raised his eyes again. "Her scars. Have you never even looked at her, Snape?"
"I have noticed them before, Potter, yes. I find there are more pleasant things to look--" Snape's words were cut off by a nonverbal silencing charm, and he realized that Potter had his wand in hand below the table.
"Don't ever say that again." Potter's voice was low and firm, yet without a trace of overt threat or menace. It sent a chill down Snape's spine, for he knew it was the last voice that the Dark Lord and many Death Eaters had heard. Snape knew intellectually that Potter had become a great sorcerer, but he did not understand the extent of his power until that moment.
Snape felt the Silencio release his throat, but was still speechless. Potter stared at him a moment longer, as though appraising whether he should simply kill Snape now and save himself the hassle of needing to do it later, then he tipped his head unconcernedly. "You can believe whatever you want about her injury. But keep it to yourself. She's quite aware that people look at her in horror. Keenly aware. She doesn't need you or anyone else reminding her."
Snape found that he had lost the rest of his appetite. "I suppose not," he mumbled, after clearing his throat.
"Her wound is magical, obviously," Potter continued conversationally. "They're not really scars, you see, they're the curse itself. It's trying to burrow deeper to finish her off. She's constantly Charming it back. Did you know that?"
Snape shook his head wordlessly.
"I've never seen it reach all the way across her throat before, and I've been watching her for over ten years."
Snape was about one sentence away from squirming in his seat, and it galled him. "What you're saying is impossible, Potter! What curse can last that long?"
The younger wizard's eyes lost their focus and he sighed deeply. "Black Lightning."
Snape gripped the table with both hands until his knuckles were white.