A/N: I am horrifically sorry that there has been such an impossibly long delay in this story. I won't go into the reasons for the initial delay, except to say they were out of my control, but (embarrassingly) after they abated I … basically forgot I hadn't posted the rest of the story. So I hope to get it up and complete over the next few days, to make up for it.

It had been so long since Severus Snape had managed to achieve more than a few hours uninterrupted sleep that he found it no hardship to be up and dressed well before the time of six in the morning he had given the boy Rowland.

Granger's earnest face, her touch burning through his coat as if it were its own kind of Dark Mark. Do you have nightmares?

The kind that would send white streaks through that wild hair of yours, Granger.

The kind he would bite off his own tongue before he shared with Hermione Granger, so convinced her limited life-experience had shown her the depths of depravity people could sink to. Or her Muggle friends.

Please, Severus … we're friends …

Snape shuddered, and shrouded himself in the Invisibility Cloak. If it is truly sufficient to hide the wearer from Death, then surely it's capable of concealing them from memory?

He'd had two days to consider how to address the problem of the three first year students deducing his location, once he and Granger had overheard their conversation. Initially, the solution had seemed simple: remove himself to the Room of Requirement and remain there for the rest of the school year. That, however, would leave him without his wards and, as blithely as Potter and his friends had taken to calling on him unexpectedly, Snape had little desire to be unable to shut them out if he chose.

In retrospect, the situation had been foreseeable the moment he had taken the decision to reveal himself to Granger. Indeed, given Minerva's meddling, that may only have brought the inevitable forward somewhat. Once the unsubtle Gryffindors had began visiting him, it had only been a matter of time before someone saw them — a situation Snape had to admit he himself had aggravated by exposing the existence of someone to the students through his marking.

Ultimately, he'd decided that if the students believed him to be a teaching assistant, he might as well impersonate one. As long as no-one saw him, it was unlikely an eleven-year-old would be able to deduce his identity from voice alone.

He was three minutes early to the Potions classroom, but Michael Rowland was already waiting, shivering slightly in the early morning chill. Snape frowned at him as he slipped his wand from his sleeve and out from under the edge of the cloak. A quick warming charm, and the boy stopped quaking. An Alohomora and the door opened.

"Inside, Mr Rowland," Snape hissed softly.

"Yes, sir," Rowland yelped, and dived through the doorway.

Snape closed and locked the door behind them. He had no intention of removing Potter's Invisibility Cloak, but nor did he have any desire to be accidentally overheard by an older student or, Merlin forbid, a teacher. Hogwarts still recognised his authority enough for him to be confident that it would open for no-one, except perhaps Granger. "Page seventy four." Another flick of his wand, discretely extended beyond the cloak. "The storeroom is unlocked."

"Yes sir," Rowland said again.

Snape leaned against the door and watched the boy as he set out his ingredients. It was clear Rowland hadn't lied, or bluffed his way through, his explanation of the relationship between Ash Muddler Potion and Cinderjuice. As Snape knew very well, the brewing instructions in the textbook for Cinderjuice were incomprehensible unless read with an understanding of the same steps for Ash Muddler. It was one of the reasons the two potions were included in the first year syllabus — comprehensively different ingredients, similar effects, almost identical brewing processes. An introduction to the concept of theory.

Of course, he would not normally have instructed a class to brew Cinderjuice before Ash Muddler Potion, but the congruence between the ingredients for Cinderjuice and the ones for the Solution to Hiccoughs had been irresistible. Disappointing that Granger failed to realise it at the time.

His lips turned down. It was not the only disappointing thing Granger had done recently.

"Wait, Mr Rowland. Read the instructions again." Despite the fact that this entire exercise was designed to allow Rowland to filch the supplies he'd need to brew Hiccoughing Potion, and that Cinderjuice was fortunately not prone to explosion on improper brewing — unless there's a Neville Longbottom involved — Snape couldn't watch the boy make a botch of the potion without intervening.

Rowland peered down at the page, and then, with a muttered imprecation, hastily stirred the mixture in his cauldron widdershins twice. Snape drifted silently closer, until he could see that the potion was thickening properly. Nearly twenty years of teaching having given him a close-to-preternatural ability to spot a suspiciously bulging pocket — even under a school robe — he could also see that Rowland had taken the opportunity Snape had deliberately given him to stuff his pockets with ingredients while in the storeroom.

Securely invisible, Snape allowed himself a small smile. Of course, they will still need to find somewhere to brew. The location of Granger's Polyjuice experiment would no doubt suit, but he had no idea of where it had been, and no interest in engaging her in conversation, after her trick the previous day.

Trying to help. Merlin preserve him from Gryffindors trying to help. If Granger's admittedly-plausible theories had any foundation, there were far better ways to address them than her support group. Yes, it was true that his dreams had grown virulently worse recently, coinciding with the curse — and he was annoyed that it had taken Granger to point out the connection — but if there was a connection, he had only to ask Minerva McGonagall to Obliviate him, and it would be gone. Preserving the memories for the Pensieve first would ensure he could refresh the memory at a later date, even if Minerva was unable to reverse the spell.

He should not have agreed to even consider returning to Granger's absurd little group. Muggles may have no efficient remedy to unpleasant memories and troubling dreams, but Granger needs to remember more often that she's a witch. It was annoying to realise that the obvious solution hadn't occurred to him either, until today, but of course, there was no reason for him to admit that to Granger.

Rowland interrupted his thoughts. "Sir, I think it's ready."

Snape surveyed the contents of the cauldron. "Passable," he said. "Do you … dare to test it?"

Rowland gulped a little, but nodded.

"You will find candles in the storeroom. Fetch one." That will give the boy the chance to pocket any ingredients he might have forgotten. "Have you studied Incendio yet?"

Rowland returned with a candle, which he set on the desk. "No, sir."

Moving behind the boy, Snape let the Invisibility Cloak part enough to ignite the candle's wick. "Coat your palm with your potion, and hold it over the flame."

The door behind him opened, and Granger's voice said sharply, "Mr Rowland, what by Nimue's kneecaps do you think you're doing?"

Rowland spun around, forcing Snape to take a step back to avoid him. "Professor! I was just —"

"How did you get in here?" she demanded.

"I let him in," Snape said, and had the satisfaction of seeing Granger jump. "Mr Rowland was about to test his Cinderjuice potion."

She frowned. "I'm not sure I can allow a student to risk hurting themselves."

Snape sighed. "Professor Granger, the boy can hardly immolate himself with a candle flame. Any slight singeing can be easily dealt with by Madam Pomfrey. And how else is the efficacy of the potion to be tested?"

She bit her lip. "I'll test it," she said at last.

"Professor!" Rowland's eyes were wide, his expression horrified.

Snape smiled. "An excellent suggestion." The memory of mildly injuring himself, should the potion fail, would be an excellent reminder to Rowland to take care while brewing, but the memory of injuring a teacher will be a far better one. "Remember, Rowland, if you pursue a career in Potions, people will depend on your ability to protect them from far worse than a candle."

He swallowed hard, and nodded. Granger pushed up her sleeve, sadly without the theatrical flair that Snape himself would have used. He was pleased to see, though, that the scar on her arm had already faded to such a degree that in the dim light of the Potions classroom it was invisible. She dipped her hand in Rowland's creation, shook the excess off, and then passed her hand across the flame. Rowland appeared to be holding his breath. He let it out in a gasp of relief when she turned to him with a smile. "It appears your Cinderjuice is effective, Mr Rowland. Now run along before you're late for breakfast."

"Yes, Professor," he squeaked, and bolted. At the door he turned back. "And thank you, sir!"

The moment he was out of the classroom, Granger waved her wand and slammed the door. "Just what do you think you're doing?"

Snape removed the Invisibility Cloak and draped it over one arm. "Teaching."

She raised her eyebrows. "I thought we discussed this?"

"Granger, I am not one of your students, so kindly stop speaking to me as if I were," Snape snapped. "The boy came to me, and thank you, by the way, for the carelessness which betrayed my location to observers."

"You could have ignored him."

Snape shrugged. "It hardly seemed worth it. Besides, he needed to learn to brew Cinderjuice."

She frowned. "Did you give him the opportunity to pocket a few extra ingredients?"

He set the cloak down on the desk, leaned back against it, and folded his arms. "Of course I did. And he took it." He paused. But, damn it, the children need to know. "He will need somewhere to make the Solution to Hiccoughs. Where did you brew your Polyjuice?"

"The Second floor girls' lavatory," Granger said. "Moaning Myrtle's Bathroom."

Snape pursed his lips. "How are they to be directed to it?"

Granger smiled. "If Maisie Wilkins doesn't know by now that no-one ever uses that bathroom because of Myrtle, and doesn't work out it's a perfect hiding place, she's not the girl to find the Quidditch Key. It's one of the things the Prefects tell you, on your first day." She shrugged a little. "I imagine it cuts down on the hysterical screaming and running about when students find out for themselves. Having a ghost pop through the door to say hello when you're on the loo can be a bit off-putting, if you're not expecting it."

"I can only imagine it would be somewhat off-putting if one was expecting it, as well," Snape said. Granger grinned, and he sternly reminded himself that he was furious with her over her deception. "Then the next stage is managed as well as it can be," he said frigidly. "I'll leave you to prepare for your morning lessons." He picked up the Invisibility Cloak.

"Wait a moment, Severus," Granger said before he could put it on. "How much help did you give Rowland?"

He turned with a sneer. "I was unaware we were on first name terms."

Granger coloured slightly. "Professor Snape. Did Rowland brew that potion on his own?"

"I drew his attention to the instructions when he seemed to be straying from them." He glared at her. "As you were able to see, he was not traumatised nor scarred for life by the experience."

She seemed unaffected by his glower. "He's an excellent student. You always treated good students with less vitriol. Except me, of course, but I guess I caught some of the spill-over splash from how you treated Harry."

Snape examined his fingernails. "By all means, let us revisit the topic of your school years. Nothing would give me greater pleasure than hearing yet another ill-informed critique of the teaching methods that saw you receive an 'O' in Potions for both your O. and your N.E. ."

Granger had the gall to look exasperated. "That's not the point, and I don't know how much more clearly I can tell you that it's not the point."

"There's a point?" Snape raised his eyebrows. "An actual point, to your meandering chuntering? I wait with bated breath to be amazed."

She frowned. "The point, Professor Snape, is that treating one good student moderately well doesn't prove to me that you can treat all my students with the respect they deserve."

"Respect?" He didn't even need to try to infuse the word with acid. "Students?"

"They're people, young people, and treating them like intellectually disabled flobberworms because they aren't learning as quickly as you'd like —" She stopped, and shook her head. "Never mind. It's a lost cause."

He scowled at her. "Indeed. You seem utterly incapable of understanding that it is your students who should treat you with respect, not the reverse. No wonder you have problems with discipline."

"I do not have problems with —"

"And were you not only a few days ago complaining to me about the disrespect one Fiona Firesmith showed you?" Snape enquired silkily. "I assure you, no student, from my own House or any other, would have dared such a thing in my classroom."

"Oderint, dum metuant," Granger snapped.

"Protego!" His wand had dropped from his sleeve into his hand as the first syllables of her incantation left her lips and the protective spell had the full force of his will behind it. Granger stumbled back, drawing her own wand, face white and eyes wide. They faced each other, his own black wand pointed at her face, her slender vine-wood one levelled at his chest.

"Professor?" He read the word on her lips as much as heard it dimly through the roaring in his ears. "Severus?" Slowly, she lowered her wand, and then went so far as to set it down on the bench beside her.

Snape lowered his own, but wasn't as foolish as she was, to set it aside. "What was that spell?"

Her forehead wrinkled. "Spell? Oh — it's just a quote. Not a spell. It means 'let them hate me, so long as they fear me'. A Roman emperor said it, at least, someone wrote that he said it, that's the thing about ancient history, you never quite know —"

"Granger, you're babbling." The students' stools were too low for Snape to sit on one and retain his dignity, but he was uncomfortably aware that his knees were in danger of giving out beneath him as his whole body trembled with the aftermath of adrenaline. He drew one closer and sank onto it, giving Granger a glare that dared her to comment. A quote. He'd come within a hair's-breadth of hexing her over nothing more than a quote. Thank Merlin I only cast Protego. It could have been anything. There'd been no decision, no thought — only instantaneous reaction and the reflexes of fighting for his life flaring through his body.

"I'm sorry," she said quietly. "Most spells have Latin as a base language — it's why I found it easy to learn a bit of Latin, when I tried — and I spend so much time in the Muggle world that I never really thought through how it —"

"Still. Babbling." Snape bit out. His arm ached, and he had to stop himself from pressing his palm over the Dark Mark's scar.

"I would never attack you," she said quietly. "Not even as a … a joke or something."

"You did so the first day we met again," Snape pointed out.

"I didn't know it really was you at the time," Hermione said. She was still pale, and Snape could imagine the effort of will it had taken her to set aside her own wand while facing his own.

Yet she did it. She had behaved far better than he had. The words had to be said, as repugnant as they were. "Granger, I — "

"It's alright," she said quietly. "You were startled."

"Hardly an excuse."

"I would have done the same, a few years ago. Before —"

Snape closed his eyes wearily. "Spare me another enumeration of the virtues of your Muggle methods."

"You promised you'd try."

His eyes snapped open. "I did not. I told you I would consider your suggestion. On reflection, a far more appropriate course of action is to ask Minerva to Obliviate me."

She gasped. "You can't do that! You have no idea what losing memories could do to you!"

He raised an eyebrow. "I trust Minerva's abilities."

"That's not what I mean. Our memories make up who we are. You're not talking about losing the last five minutes, you're talking about pulling the threads out of the whole fabric of your self." She paused, and then took a deep breath. "I know, you know. I did it to my parents. I did it to keep them safe. And it did, but even when I restored their memories of me … they'd been living as different people, people without a daughter, and even when they knew it wasn't true, it had changed them. I did a lot of —"

"Reading?" Snape asked acidly.

"Research, yes, about why that was. Our brains are basically chemistry and electricity, even witches and wizards — we're still human, after all — and when you change those pathways, there can be permanent, physical changes. It's unpredictable. Some scientists say that we change our memories ourselves each time we remember them. And I think that when we build a sense of self out of memories with some key bits missing, we can't just switch straight back when we get them back." She leaned forward. "It would be a kind of suicide. I didn't know when I did it to my parents, but I do now. If you take important parts of a person's past from them, it's like killing the person they really are. After all, why didn't you ask someone to Obliviate you, when Harry's mum was murdered? Was it just because you wanted to remember her, or did you suspect that you would be a different sort of person if you didn't?"

Snape glared at her. "That is none of your business. And it's irrelevant. You've theorised that my recollections of … certain events are linked to a curse that threatens my life. That was not the case with Lily." It was almost true. True enough for Granger, anyway. There was no need for her to know how closely and for how long he had clutched the pain of Lily's loss, protecting it as carefully as he'd protected Lily's son, the only parts of her he could keep alive. The least she deserved.

But did Charity Burbage deserve less? He had been locked in misery when she started at Hogwarts, frozen by his all-consuming hatred — of Voldemort, of Dumbledore, of his students and their appalling naivete, of every useless person alive and drawing breath who wasn't Lily … of himself. His colleagues had treated him with, at best, icy civility — except Albus Dumbledore, whose company Snape had barely been able to tolerate after the Headmaster's failure to protect Lily.

Charity had ignored his history, and his reputation, and when he responded to her overtures of friendship with savagery and sarcasm, she had simply ignored that too. He had been unable to drive her away until, somehow, he'd come to realise he didn't want to. Her cheerful insistence on treating him as if he were a normal person, incomprehensible as it was to everyone else including himself, had given him a tiny finger-hold on a life where he might hope to one day be more than just a man who'd destroyed the one thing that mattered to him.

Please, Severus … we're friends …

He realised he had been silent too long and that Granger was watching him, an expression he couldn't read on her face. To his horror, he could feel his eyes prickling with the presage of tears. Granger may be right about this thrice-bedamned curse and its effects. How long had his mind been wandering, completely undisciplined, as if he'd never learnt Occlumency at all? If I had made that sort of childish error when faced with Voldemort, rather than Granger, I would be long dead. Deliberately, he cleared his mind, erasing thoughts of Charity like chalk from a classroom blackboard. He concentrated, as he had for so many years, only on who he needed to be and what he needed to think and feel in this moment. The prickling receded.

"Severus." Granger reached out as if to touch him, but stopped as he drew back. "However bad it is, it's better to deal with it than pretend it can be erased. Believe me."

He raised his eyebrows and said as coldly as he could, "As you know from your vast life experience?"

"I've had to deal with more things in my life than some people much older than me," Granger said mildly. "And I'm only giving you your own advice back to you, you know. You forced me to face the memory of Bellatrix Lestrange at Malfoy Manor. What if I'd had it Obliviated?" When Snape remained silent, she pressed her advantage. "You could have just accepted it when I didn't want you to see my scar, but you knew something was wrong, and you made me face that there was. If I'm right about the curse on you, you need to do the same thing. Face it, so you can fight it."

Snape narrowed his eyes. "With your Muggle methods."

"Believe it or not, people who can't rely on selective Obliviation, Occlumency and Pensieves have actually come up with some good alternatives. Just like they have with parcel post and telephones and video cameras."

He sniffed. "Inferior substitutions."

She drew a sharp breath, and then visibly composed herself. "Perhaps. But answer me one question, Professor. If you can answer yes, honestly, I'll never mention it again. As far as Obliviation is concerned — the man you would be if you forget — is he someone you truly want to be?"

Snape drew breath to say Certainly, in his most cutting tone, but the word wouldn't pass his lips. That man would bear no responsibility for Charity's death, for the deaths of the others I couldn't save.

That man would remember his time as Headmaster of Hogwarts as a year in which nothing worse happened to students than the occasional detention with Hagrid.

He would know only as much of the death of Albus Dumbledore as he'd been told.

He would never know how thoroughly he'd betrayed not only Lily, but Lily's memory — that he'd been willing to send her son to his death.

Who would that man be? Someone who could sleep soundly, certainly; someone who had never made terrible choices when torn between impossible alternatives. Someone certain of his judgement, confident of his course of action.

A man with few, if any, doubts.

Snape had known men with no doubts. He'd served and spied on one for years.

"No." Snape's voice sounded odd to his own ears, rusty, as if he'd been silent for far longer than a few seconds, although Granger didn't seem to notice it. "No. I would not choose to forget — but to save my life, I will."

"And if there's another way?" Granger asked softly. "Even a Muggle way?"

"You said one question, Granger," he said repressively.

She only looked at him, pale skin luminous even in the half-light of the dungeons: this meddling, insufferable busybody of a know-it-all, who had survived Bellatrix Lestrange and defied Voldemort — and who had laid her wand down while facing his own.

"Very well," he said stiffly. "If you insist."

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Author's Note: Obliviation is treated much more lightly in the canon than I treat it here, but to be honest, the idea of someone erasing parts of my memory gives me the creeps.