"They got through!" Hermione Granger shrugged out of the Invisibility Cloak, or at least partly so — one shoulder and arm remained shrouded and invisible. "They got into the second room and worked out the levers!"

Snape looked up from the scrolls in front of him "Congratulations."

She didn't seem to notice she'd left herself half-invisible. "They had a close call with Mrs Norris but I managed to grab her in time."

Snape raised his eyebrows. "Do you need a salve for your cat scratches?"

Hermione smiled. "She's much easier to deal with than Crookshanks when he's in a mood." She moved towards the fire and held out her one visible hand to its warmth. The impression was oddly disquieting, as if she'd taken a some horrific wound in the War and it had only now made itself apparent. "After they got out, they were talking about needing a broomstick, so they worked out the levers."

Snape rose to his feet and stalked towards her. "I hope they brewed enough for three trips through the corridor." He took hold of the Invisibility Cloak and drew it from her shoulder, restoring the whole and unharmed Hermione Granger. "Since the broomstick will not work."

"I think so," she said. "I couldn't get close enough in the bathroom to see, exactly, but the vial looked full enough for well over nine doses."

Snape folded the cloak over his arm. "A successful evening, then."

"I hope so." She smiled up at him. "How long before they work it out, do you think?"

He raised his eyebrows. "Using their current performance as a baseline? I expect only a few weeks. But the final clue should delay them until after the holidays." He sniffed. "Only Colin Aitkins shows any sign of being able to apply himself to research."

Granger's smile widened. "And yet, you prefer Michael Rowland."

He took a step back from her — no, he moved towards the chair, to lay the cloak on it, Coincidentally, it was away from Granger. "I don't prefer any of your Terrifying Triplets, Granger. I'm only involved in this lunacy to ensure you don't create a situation where students are at risk."

"And Rowland has an admitted talent for Potions."

"He has the ability to comprehend and follow instructions," Snape said. "That does not automatically translate to a talent for Potions, although it can pass for such at his age, given the simplicity of the recipes taught to first year students."

She turned her back to the fire. "They're fascinated by you, as well, you know. Or, not you precisely, but with who you really are." She smiled. "Their current working theory seems to be that you're one of the students who fought in the Battle of Hogwarts, horribly injured defending the school, but they'll work out you can't be if they look into it. Rowland has already twigged to the fact that you're too old, from your voice."

Snape closed his eyed and pinched the bridge of his nose. "Wonderful," he said sourly. "Not only my former students intruding into my well-earned privacy, but soon my current ones, as well."

"It's your own fault," Granger said, entirely too cheerfully. "You really are a terrible recluse."

He raised his head and gave her a cold stare. "Given the sum total of my current ambitions is to be left alone, I hardly think that's something to regret."

"No, I meant, you're terrible at being a recluse." She grinned at him. "Popping up in my classroom. Wandering the building. Letting both me and Harry find you in the Room of Requirement. Teaching classes. It's almost as if your heart isn't really in it."

"Don't be absurd, Granger," Snape sneered. "As any one of my former students could inform you, I don't have a heart."

She tilted her head a little. "Would it really be so bad, if people knew you were alive?"

He raised his left arm a little, forearm towards her. "Have you forgotten the evidence that people knowing that I live is very bad news indeed?"

Granger winced. "Alright, point. But that's one person, who clearly does already know you survived. Why not let everyone else know, too?"

Snape raised his eyebrows. "Flattered as I am by your estimation of my abilities, I must admit there is a limit to the number of death wishes I can fend off at any one time."

"If the Ministry cleared you …"

"If," Snape said acidly. "Such a very certain word to gamble my future and my freedom on."

"Harry would testify for you. The Headmasters' portraits would testify for you." Hermione ticked each point off on her fingers. "Luna and Ginny and Neville would tell the Ministry that you protected the students from the Carrows as much as you could —"

"Yes, only the occasional Cruciatus," Snape snapped. His arm ached. "Such a legacy, of my time as Headmaster, that students were not tortured quite as often as they might have been."

"You could let Kingsley view the memories you gave Harry."

"By now you must have learnt that Pensieve memories can be edited by a skilled enough Occlumens."

"But you didn't —"

"But they'll say I did," he snarled. "Granger, when I was the age Potter was when he defeated the Dark Lord, I, instead, chose to serve him. He talked of killing Muggle-born witches and wizards, and I was silent." The scar of his Dark Mark burned and throbbed, as if Voldemort was using it to summon him once more. "I delivered the prophecy that sealed Lily's fate to him, and if he had decided that Neville Longbottom was the chosen one and not Harry Potter, I would no doubt have stood by. I was a Death Eater, Granger, no different from any of them."

Hermione had gone pale as he spoke. "But you —"

"Turned on him?" Snape spat. He pressed his hand over the Dark Mark, trying to quiet the screaming nerves. "For Lily. Only and always for Lily — not for all the other children, children like you, who would have been swept aside when the Dark Lord came to power. Not for those he killed or would have killed. Not —" The Mark was searing now. He clutched it and tried to breathe through the waves of pain. "Not for any idea of what was right, or good, Granger, or for any revulsion of what he was or what he did."

"That might have been who you were," Granger said. "But it isn't who you became."

Snape gave a harsh laugh. "You have no idea who I became. I served the Dark Lord through two wars."

"Only because you wanted to stop him," she said stubbornly.

"Do you have the faintest inkling of what I did, to save my own skin, to keep the Dark Lord convinced I was a loyal Death Eater?" The pain was all-consuming, no longer limited to his arm, scorching through him as if his very bones were its conduit. He forced himself to keep speaking. "The deaths I acquiesced to? The torture I was indifferent to? The —" A spike of agony robbed him of breath, and he doubled over, gasping.

"Severus!" Hermione hurried to him. "Here, sit —" She took his arm. Snape jerked away from her, lost his balance, and landed awkwardly on the carpet with a jolt that made any pain he'd experienced so far a pleasant memory. He managed — just — not to scream. Dimly, he was aware that Hermione was kneeling beside him and he managed to turn his head away from her. So much for my dignity. Yes, I might be grovelling on the ground in front of Hermione Granger, but at least I'm not screaming. Such a triumph.

"Severus," she said again. "What can I do? How can I help?"

Get out. He ground his teeth together, knowing that any attempt to speak would utterly defeat his efforts not to give voice to the pain that beat through him, hammered down on him, nailed him like an insect skewered by an etymologist's pin.

"Look at me." Her hands, cool and soft, were on his face as she tried to turn his head. "Severus, please. You must listen to me."

Shut up and get out. But, oddly, her touch was the only thing he could feel besides the cold fire consuming him. To his horror and humiliation, Snape found himself turning into it. Hermione was kneeling over him, tears streaming down her face, mouth twisted and quivering in an effort not to burst into outright sobs. It was an expression he'd seen with satisfaction on the faces of countless students over the years, but now all Snape could think was No …

"Clear your mind." Her voice was choked but steady. "Use your Occlumency. Severus, please."

Severus, please … we're friends …

He lost the battle, then, his back arching and a scream tearing out of him, as Charity had screamed. Hermione cried out as well, her tears raining down on his face, and then, to his utter shock, she snatched out her wand and pointed it at him. "Legilimens!"

No! There were so many things she must not be allowed to see, to know — that he couldn't bear to have her know — he made his mind blank as an empty blackboard, as still as a frozen pond, as clear as the air at midwinter's midnight. The old, basic tricks of beginners Occlumency answered him, even now, instantly and flawlessly. I am nothing, I am no-one, I do not think, I do not feel …

I am not here.

Her assault on his mind was weak, clumsy — and brief. Snape held himself suspended in perfect stillness a moment longer, until she set down her wand, and then, cautiously, he allowed himself to think and feel and know again, examining each piece of awareness he allowed back in to his mind carefully. Fury, at Granger's attempt to invade his mind. Concern, that she had so poor a grasp of such an essential tool as Legilimency — no, contempt, not concern. Contempt at her lack of skill. Unease — no, irritation — at the distress written so clearly on her face.

But not pain. Weakness, yes, exhaustion as if he'd been several brutal rounds with the Cruciatus curse, but that was all. He raised himself on his elbows, as a first step toward managing to escape the humiliating position of sprawling helpless at Granger's feet.

"Rest," she said, trying to stop him with a hand on his chest.

Snape grasped her wrist and removed her hand from his person. "If you are under the illusion I intend to remain prone on the carpet, Granger, disabuse yourself of it immediately."

She bit her lip. He tensed as she picked up her wand again, but she only used it to draw his armchair across the room. "Here."

Snape used the arm of the chair to haul himself to his knees. Granger pulled his arm over her shoulders. He forwent the rebuke her presumptuous impertinence deserved, grudgingly aware that without her assistance he was destined to remain on his knees for quite some time. With the arm of the chair and Granger to support him, he managed to raise himself enough to sink into the chair in something approaching dignity.

"Can I get you anything?" she asked. "Water? A potion of some kind?"

"I have Tilney for such things," Snape reminded her. Be a witch, Granger, not some less-useful and far more annoying approximation of a house elf.

"I need to see your arm." She stretched out her hand towards his. "That was the curse, you must know that. I need to see … if it's worse. How much worse."

He narrowed his eyes at her, irritated that she had clearly managed to think more clearly and more quickly than he had. The pain he had automatically translated into the old, familiar burning of his Dark Mark … the cascade of unwanted, unsought memories and emotions … Of course it was the curse, you dunderhead. Grudgingly, he unfastened the cuff of his shirt and pushed up the sleeve.

"Oh, thank Merlin," Granger cried as the movement revealed an oval of withered flesh that was no larger than it had been the last time she'd insisted he show it to her. "I thought —" Her irritating weeping began again.

Snape, too, had expected to find his whole arm grey and decaying. He yanked his sleeve back down. "Apparently Occlumency is effective against it. Interesting. I would say your theory is looking less unlikely. This curse, like Bellatrix's on you, is designed to provide more than mere physical torment. Do stop snivelling, Granger."

She took a deep breath and pressed the heels of her hands to her eyes for a second. "You don't understand."

He raised an eyebrow. "That you greet both good and bad news with counterproductive displays of emotionalism? I believe I have a firm grasp of the phenomenon."

Granger lowered her hands, and shook her head. "I thought I'd killed you. I should have realised — I should have changed the subject — I thought it would do you good to at least start to talk about it, but I should have known it was the worst possible thing —"

Snape frowned, trying to find some thread of logic in her jumble of half-voiced thoughts. "Granger, according to your theory, my assailant today regained access to his conduit and renewed his assault. I assure you, changing the topic of conversation has never been shown to be an effective defence against an attack by Dark magic."

She bit her lip. "That's not my theory." Her voice was little more than a whisper. "I thought — I thought you'd be less likely to dismiss me out of hand if I sort of worked up to it. So I … I lied to you." She took a deep breath. "Harry worked out who was casting the curse, you see, once we realised the way that combining a death curse with a Protean charm would change it."

He stared at her. "You know who's doing this to me? You knew, and said nothing? Who is it?" When she hesitated, he grasped her wrist and hauled her closer. "Tell me this instant or I will rip the knowledge from your mind and I promise you, it will not be an experience you enjoy."

Granger took another deep breath, her gaze fixed on his. "It's you. Severus, you're cursing yourself."

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Author's note: As you can probably tell, I've taken the information about Occlumency in the canon and run with it (as I do with so much else). Snape tells Harry in Order of the Phoenix about Occlumency having both a basic application of making the mind blank, and an advanced form of appearing to hide nothing by thinking and feeling only what you want to be perceived. Snape must have been a master Occlumens, to survive spying on Voldemort, which suggests to me he was also a master at controlling and editing his own thoughts and emotions.