"But —" Hermione stopped as a chilling thought struck her. "Professor, I thought the Marks only answered Voldemort. For him to call people, or for them to summon him. If someone is reaching Dark Mark to Dark Mark — does that mean … Is it him? Is he … is he back?"

Her voice shook as she said it, and she was certain that Snape would mock her for it.

To her surprise, though, he spoke without even a hint of sarcasm. "He is not back, Professor Granger. He is dead, and forever gone." He paused, and then went on with uncharacteristic hesitation, "I would say he cannot hurt you any more, but memories do retain a … certain power. No, I believe that someone else has managed to find a way to activate the lingering traces of the Mark to their own ends."

"To kill you," Hermione said, because that greying patch of flesh resembled nothing so much as the killing curse that had struck Dumbledore.

"Yes." Snape rubbed at the place where the curse was, and Hermione didn't think he was aware of the gesture. "I thought at first perhaps it was more general, that someone … less forgiving felt that the Ministry wasn't dealing with the surviving Death Eaters harshly enough."

Hermione nodded. "And was killing them off, and you got included accidentally."

"Exactly. However. Minerva visited Azkaban under the pretence of concern for the rehabilitation of some former students, and none were cursed."

"I saw Draco just a few weeks ago, and he didn't seem at all unwell," Hermione said.

"Good to know," Snape said quietly. "So, is your curiosity finally satisfied? Can you finally leave me in peace?"

"How long?" she asked quietly.

"I can contain it, for now," he said. "Perhaps a year. I have not yet abandoned hope that it will be long enough to transform you into a competent teacher."

"Are you in much pain?"

"Only intermittently." Snape gave her a sharp look, and the acid was back in his tone as he said, "And these period of inconvenient weakness are also intermittent, so kindly put out of your mind any youthful fantasies of playing Florence Nightingale."

Hermione felt herself blush. Well, he did wake up to find you mopping his unfevered brow… "I promise I won't try and nurse you, if you promise not to be so stupid as to get out of bed when you're barely able to stand," she said tartly.

"A bargain I will cheerfully make."

"Good." Hermione stood up. "Then I'll leave you to get your rest."

She was almost at the door when his quiet voice stopped her. "What was it you wanted to ask me?"

Hermione frowned, and turned to look at him. "What do you mean?"

He gave a flick of his fingers in her direction. "Before. When you were hammering on the door of my bedroom. You wanted to ask me something."

"Oh." It felt like hours ago. "It's nothing, really — I just wondered — today was so exhausting. When does it get easier?"

"Never," he said, and the corner of his mouth turned up. "But do enjoy this first week, Professor Granger. It's the best of the term." He raised an eyebrow. "You see, from next Monday, you'll have homework to mark, once your classes are over."

"Oh, Merlin's pants," Hermione said with feeling.

Snape made a sound that it took Hermione a moment to realise was a laugh. "And your first year class? The Polyjuice demonstration?"

"Went really well, I think. The student played her part terrifically, and the rest were quite enthusiastic about brewing the Boil Cure afterwards. I think knowing they are working towards something as spectacular as Polyjuice potion inspired them."

"Melted cauldrons?"

"None," Hermione said a little smugly, keeping to herself the fact that she'd had to almost sprint across the classroom to keep one of the Hufflepuffs from making the exact same mistake Neville had in their very first class.

He raised an eyebrow, as if he'd read her mind. "Impressive."

"So you were wrong," Hermione couldn't resist saying. "It wasn't ambitious, after all."

"How very Gryffindor of you, Granger," Snape said, sounding bored. "To think there's anything wrong with ambition." He flicked his fingers in a shooing motion. "Good night."

"Good night, Professor," she said, and left, closing the door gently behind her.

Pausing only to return the armchair to its proper place, Hermione left the Room of Requirement and went straight to the Library.

There were still students there — mostly from the older years, although Hermione saw Colin Aitkins and Maisie Wilkins sitting with another Hufflepuff and a Ravenclaw from the same year. She saw their heads swivel as she passed them and she was almost certain she heard a gasp when she stepped past the sign, over the rope, and into the Restricted section.

Well, Mr Aitkins, let's give you a preview of what you're hankering for, shall we? Hermione scanned the shelves until she spotted a book that would serve her purpose. It was thick and black and covered in nasty-looking stains, and chained firmly shut.

Hermione set it down on the nearest reading desk, took a firm grip on her wand, and unfastened the chains.

The book promptly levitated five feet into the air, flew open, and emitted a bloodcurdling scream that echoed through the entire library.

"Silencio!" Hermione snapped, and the shriek stopped abruptly. "And Accio yourself back down here this instant." The book fell into her waiting hand. "Thank you."

She turned a little, until out of the corner of her eye she could see Colin's wide-eyed face looking around the end of a row of shelves at her. Madam Pince was glaring at her, and Hermione gave her a sunny smile as she locked the book shut again and put it back.

Right. What am I looking for? Dark Marks … protean charms in general, I suppose … and killing curses.

Lovely bedtime reading, this will be.

Hermione had a stack of books in front of her and was deep in a profoundly unpleasant description of a nineteenth-century wasting curse when a cheerful "Hello, Professor Granger," made her start.

She looked up to see Harry grinning down at her. She smiled back. "Hello, Professor Potter. However did you know where to find me?"

"Apart from knowing what you're like?" He showed her the corner of the Marauder's Map, tucked under his robes. "Because I was up to no good, of course." He leaned down to read over her shoulder. "That's a nasty one."

Hermione's smile faded. "Yes." She closed the book. "Harry, does Auror training teach you to break curses like that?"

He nodded as he pulled out a chair and sat down beside her. "Or at least, how to go about it. It's more of an art than an exact science, especially if someone's combined the curses."

"So if someone had been cursed, with something like this or at least, something similar, you'd be able to help them?"

Harry shrugged. "Maybe. I'd probably have to call in a specialist, if it was really tricky. There are only a few really top curse-breakers, and they mostly work independently. They absolutely coin it in, although thankfully there's less call for their particular services these days."

"Now all the Death Eaters are in Azkaban?" Hermione asked, and Harry nodded. "And they are all in Azkaban, aren't they? Except for the Malfoys?"

"Azkaban or dead," Harry said. He put his hand over hers. "What's this about, Hermione?"

"Not me," she said quickly. "I'm not cursed, or anything."

"I know, you're not stupid enough to keep it to yourself," Harry said. "Were you looking for the rest of us, earlier?"

Hermione frowned. "Earlier?"

"I saw you coming out of the Room of Requirement."

"Oh! No, I —" She stopped. I promised Professor Snape I wouldn't tell anyone. And then she'd acted as if that promise meant she should help him hide, at least a little … but that was before I knew.

That he's dying.

"Harry, you know I made a promise, right?"

He nodded. "Ron told me. And that it wasn't hurting you." He studied her carefully. "It isn't hurting you, is it? Because you look …"

"It's not hurting me," she assured him. "And if I break it, I'm afraid that the person I made it to will stop trusting me. I mean, even the little that he does trust me now. And now …" Hermione bit her lip. "Now I've learnt something that makes me want to break my promise but I think it makes it even more important not to lose his trust. If that makes sense?"

Harry nodded. "Clear as mud."

Hermione's eyes filled with tears. "Harry, I'm trying!"

"Hey, hey, Hermione." Harry put his arm around her shoulders. "I'm sorry. I should know better than to needle you when you've spent hours up here with this lot. Come on. Let's get away from this stack of mouldy old malice and have a proper talk."

Hermione did feel better almost immediately, once they'd left the Library. "I shouldn't have spent so long with those books," she said.

"It gets to you," Harry agreed. "Cast a Patronus every now and again, if you're going to spend much time with them. Now, where shall we go? Room, again?"

Hermione shook her head. "No. I want some hot chocolate."

Harry grinned. "I know — your office, Professor Granger. And we can deduct points from any Slytherin we find wandering around the halls down there."

"Harry!" Hermione protested as he led the way to the stairs. "What was all that earlier about not carrying on old grudges, then?"

"I'm not!" He jumped the trick step. "But I've just taken ten points off a couple of Gryffindors I found snogging behind the statue of — who is that odd-looking chap in the third floor corridor? With the tree growing out of his head?"

"Hambledore the Barking, and that's his hat, apparently," Hermione said. "According to Hogwarts: A History he was —"

"Barking mad?"

"The first wizard to codify the process by which a witch or wizard could become an Animagus," Hermione said a bit waspishly as they turned the corner.

"Oh. Bully for him, then." They reached the last staircase to the dungeons. "Remember how Professor Snape used to manage to just appear, down here? Directly behind us, at the worst possible moment?"

"He definitely had a talent for appearing unexpectedly," Hermione said. One which he has apparently not lost. She had to suppress a smile. There was a scurrying sound from the direction of the Slytherin common room, and she cocked her head, then raised her voice. "Students out of bed after lights-out earn their House an immediate fifty point deduction."

The scurrying froze into immobility.

"Hypocrite," Harry whispered to her.

"No, a traditionalist," Hermione retorted. She put her hand on her office door and it opened. "Here we are."

Harry followed her in, and looked around at the heavy desk in wood so dark it was almost black, the shelves of mysterious ingredients, and the incongruous chintz armchairs. "I love what you've done with the place."

Hermione snorted. "I haven't done anything with the place, which I suspect is your rather heavy-handed point. I haven't had time. Anyway, the Potions Professor's office shouldn't be cosy." Not to mention, because I can't, that it felt wrong to change Professor Snape's office without the permission of the man himself. "Tilney?"

The house elf appeared, and on Hermione's request, promptly fetched them steaming mugs of hot chocolate and, Hermione was pleased to see, a plate of biscuits she hadn't asked for. Tilney is starting to like me. Once the house elf had vanished again, Hermione cast a quick Muffliato and shot the bolt on the door.

Harry picked up his mug and took a sip. "Now. You're having second thoughts about this promise, but you still want to keep your word."

Hermione nodded. "If I'd known everything, I wouldn't have made it. But if I break it now …"

He nodded. "Minerva's in the same boat, I expect."

"I think I can tell you …" Hermione bit her lip. "It isn't Professor Flitwick."

"I know that," Harry said. "Ginny told me it wasn't as soon as she'd talked to you. Would it be cheating for me to just ask you about each of the teachers in turn? I suppose it would." He paused. "Honestly, Hermione. You could have found time to brighten the place up with a throw-rug or something. I feel as if Professor Snape's just stepped out and is due back any moment."

Hermione looked around. "So do I." With rather more reason than you know.

"So this person — man, because you said he — you've made a promise to, he's been cursed, and you think a Death Eater did it." Hermione blinked at him, and Harry gave a slightly smug smile. "Your reading list, and your questions, gave it away. Well, if it's a Death Eater, it's got to be one of the Malfoys. They're the only ones still at large."

Hermione kicked off her shoes, and curled her feet under her. "Can you be completely sure? I mean, what if there was someone who kept it secret, and never got caught? Or … someone people thought was dead?" That would be an irony: the supposedly dead Severus Snape cursed by another supposedly-dead Death Eater.

"We verified all the dead by their magical signatures," Harry said. "I suppose I should say they verified all the dead, it was before I even started my training. But one way or another, all the names are ticked off. As for secret … they'd have to be very secret. The Ministry's Legilimens have been through every single relevant memory of all the ones we caught, and all the ones they couldn't help but give up." He picked up a biscuit, inspected it, and ate it in two neat bites. "These are excellent. So it's the Malfoys. I know you say Draco's changed, but Lucius …?"

Hermione shook her head. "Someone who … would know told me it isn't the Malfoys."

"Yes, but who really knows Lucius Malfoy these —" He stopped, looking at her. "Hermione. I'm suddenly having a completely mad idea."

.

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Author's note: Thank you all for reading this far! I'd love to know what you think, so if you haven't, please leave a review!