By random accident that looked like conspiracy, the Slytherins who stayed behind at Hogwarts over the Yule break were all kin to Death Eaters. Rosier, Nott, the Carrow twins, Travers, Yaxley, and Harper, whose mother was a Rowle. This did not go unnoticed by the resident Gryffindors, mostly children of Aurors not given time off over the holidays, who made it their business to shadow the Snakes everywhere they went. Someone had let a murderer into Hogwarts and that someone probably wore green.

Hermione sat by the hearth wearing her pyjamas, a robe, and two pairs of socks because the dungeon stone devoured heat. Flora and Hestia had joined her as none of the girls' dorms had fireplaces and Warming Charms could only do so much. The twins' mother had sent an enormous box of fudge, which they shared with their similarly immured Housemates. Travers, a First Year and miserably homesick, lay on a sofa rugged up in all the blankets off his bed having a sulk.

Nott, Yaxley, and Harper had collectively gone to the Library as there was safety in numbers. None of the Lions had tried anything yet but that could be because none of the Snakes had gone anywhere alone. So when Harper burst into the Common Room white faced and shaking, the idle quartet had their wands out instantly.

"De... men..." The boy wheezed.

"Dementor?" Hermione demanded, shedding her robe to wrap it around him. His skin was icy. He nodded. "Where are Nott and Yaxley?"

"Dunno." Harper mumbled, struggling with his own tongue to speak. The fight or flight instinct did not allow for eloquence. "Lost them at the old kitchens."

"I'll get Professor Snape." Hermione turned to the Carrows. "Feed him fudge until he stops shaking, light all the candles you can, and stay here."

"You're going out?" Flora knew of no grudge between her family and the Notts or the Yaxleys, and she had nothing against Theo or Corwin. However, the only person for whom she would face Dementors was already in here with her.

"Someone has to, and I'm the eldest here. Accio shoes." Hermione tried to sound pragmatic while stuffing her feet into her Mary Janes. She was going anyway, regardless of excuse and didn't stay long enough for either Carrow to object further. Neither did she blame them for locking the door behind her. Once out in the corridor, her breath misted. "Moppet!"

"Miss calls Moppet?" The house elf appeared and quickly wrapped her arms around herself. "This is bad magic, Miss, hungry bad."

"Tell the Headmaster there's a Dementor in the dungeons, please." She spoke rapidly. The witch then tore off down the hallway as fast as she could. Hermione felt a coward for not going to Nott and Yaxley's rescue herself but fended off that emotion with common sense. She couldn't cast a Patronus, and when she had asked Hogwarts about why she had reacted so little to the Dementor on the Express, the Castle's reply had been evasive.

Professor Snape answered the door immediately when she hammered on it. Slytherins were not given to beating their fists upon his dread portal. He took in Cathal Rosier's pyjamas, drawn wand, and purposeful expression, and did not pepper her with questions. The Potions Master merely raised an eyebrow at the Third Year witch.

"Harper, Nott, and Yaxley saw a Dementor near the old kitchens. Harper is in the Common Room but Nott and Yaxley haven't returned." Hermione spoke crisply, mimicking Alastor Moody's clipped diction. All the information, no gabble.

"I cannot spare the time to escort you back to your dormitory." Snape drew his wand and stepped aside to admit Rosier into his office. "Stay here until I return. Touch nothing." He ordered, aware of her interest in Potions. He did not want to return to find the Sorcerer's Apprentice re-enacted in his private chambers. The witch biddably took the supplicant's chair before the desk. The wizard chose to believe she would remain there.

As soon as he shut the door, Hermione pulled her Map out of a pocket in her robe to search for Nott and Yaxley. The Slytherin kitchens had been built during a time when older Years could dine privately in their Common Rooms. In passing through that area of the dungeons, the boys had taken an indirect route from the Library likely trying to throw off any harassment from the Gryffindors.

If the two had been thinking rationally, never an easy thing to do in the presence of a nightmare, they would've headed up back towards the first floor. She looked there hopefully. Unfortunately, the enchanted vellum showed two figures 'Nott, Theodore' and 'Yaxley, Corwin' running towards the Porticus Periculum. There was no sign of pursuit because she hadn't devised a way to include Dark Creatures in the artefact.

"Voice, can you sense the Dementor?" She asked the Map.

"There is an absence. It obfuscates the space around it. We can see only where it is not." Hogwarts replied, a tint of outrage colouring the voice. Dementors were a threat to the students and threats were unwelcome. "How did such a wight enter our domain?"

"I don't know." Hermione admitted. If she had to guess, she would've gone with one of the collapsed tunnels in the older sections of the Castle but that was entirely supposition. She didn't know enough about the physics of the Dementors to estimate how much they could compress themselves or whether they could become intangible. Everything she had read about them had said 'semi-corporeal'. They had a physical presence even if it was insubstantial. They weren't ghosts.

"You will find out." The Voice ordered.

"How, precisely?" She asked more sharply than camaraderie allowed. "Cathal can't cast the Patronus yet and you were very dodgy on why I didn't feel much from the Dementor on the train. I'm not going to seek out a nest while armed only with Cheering Charms."

"You do not feel the hunger of the fearful creatures because they cannot feed on you. That is enough for you to know." An amelioration of the imperiousness in the Voice's tone suggested there had been a switch in control. Hermione didn't know if there were distinct personalities within the gestalt being but she suspected the imprints of very powerful people lingered. A thought occurred.

"Voice, can you speak Parseltongue?" Hermione inquired, wondering if the Castle's contact with Tom Riddle had left a recent trace of his inherited ability. Of course, given Salazar Slytherin was a Founder, Hogwarts might have the ability from him.

"We cannot." A hint of ruefulness and a large serve of irritation. "When Slytherin left, he took many of his secrets with him. Nothing done with his fellow Founders could he undo but he could remove what was privy to him and his heirs."

"Bugger." She remarked. "I thought maybe the Chamber of Secrets has another exit or some malignant seep the Dementors could use. They'd definitely like the place and I haven't been able to get in, of course." Hermione stopped herself before she petulantly kicked Snape's desk. He could certainly notice a new scuff mark or a charm to remove one. "I have a memory of Ron's impression of Harry talking in his sleep. I could Pensieve that to try to imitate it myself."

"In the house that Jack built." Hogwarts said wryly.

"A bit like that." Playing Chinese Whispers with herself wasn't the most reliable way of getting an accurate result. "There's no chance Harry would tell Cathal personally." She didn't want to draw attention to the Chamber in case someone removed the basilisk. "There must be memory projection charms or something similar for the enchantment of a Pensieve. I could adapt one of those."

"You would need means of sensing the malevolences also."

"I'll add it to the list." Hermione pulled out a notebook from her robes. She always carried one as she had learned, coincidentally in Third Year, that if she wanted to remember something she should write it down. Trusting to her memory while under stress wasn't foolproof. "Do you remember what you said to me when we were at the end of the thread? I'd call it stasis but it wasn't quite that."

"There was a message from us to us sent back with you, woven in with the magic. We know it to be true but it was brief." The Voice paused and Hermione could almost hear it editing what it was going to tell her. She wasn't going to stamp her foot to demand she be told all but one day she would find out. Secrets were poisonous and secret magic doubly so.

"You said an Avada stains the fabric of reality, to paraphrase." She prompted when the Castle's silence lengthened. Talking to a disembodied voice gave her no visual cues to guess Hogwarts's thoughts. The attenuating pause suggested more careful composition.

"Once there is a death, there will always be a death." The words were heavy, adamantine. "We comprehend you wish to be a Valkyrie but the Killing Curse is not deflected lightly. Choosing the slain is not your remit. Perhaps you could sway the spell by inches."

"Harry was nearest Sirius." Hermione had stared, they'd all stared, as Sirius had almost drifted into the archway. Remus had rushed to hold Harry back. She sighed. Diverting Bellatrix's curse might well hit Harry, and on that possibility alone she couldn't risk it. "I should find the bloody rat and do him in now before he brings back his Master."

"Why have you not?"

"Because that bastard will find a way to resurrect himself. If I kill Pettigrew, I won't know when Voldemort comes back. He could take years to piece himself together or someone more competent might find him." The simple truth was she had to wait, to bide her time until after the rite at the cemetery. Once Voldemort was corporeal again, he could be slain. Harry would have allies then. And the damned Prophecy would be fulfilled.

"He craves this place." The Voice spoke with an echo of dread. "He has no right. A thin line of blood does not grant him sovereignty."

"Harry defeats him. I saw that much." Hermione reassured. Her eyes caught movement on the Map as 'Snape, Severus' returned to the Slytherin Common Room with 'Nott, Theodore' and 'Yaxley, Corwin'. "The Professor will be back soon." She watched the little figures move down the corridor. "I feel a wuss for not going after them myself. Gryffindor urges."

"You are no longer a Lion." Hogwarts said with less gentleness than Hermione would have liked.

"I haven't forgotten." Every day she dressed in green she was reminded she had left her old self behind. Hermione put the Map away and waited for Snape to return, not touching anything as commanded. She'd need to order more nettles and some Dittany. Their classwork on undetectable poisons, so named because the commonly used detection charms didn't register their presence, was fascinating. First time around she hadn't appreciated how the poisons could be integrated with so many other potions. This go, she had leisure to investigate in depth.

"Miss Rosier." Snape flung the door open and found to his mixed pleasure and regret that the witch was in the chair he had indicated. He was so accustomed to defiance from his charges he was mistrustful. A flick of his wand confirmed none of the security charms had been breached. Severus kept the most dangerous ingredients in his private study to guard against pilferage. He could with five minutes and what was contained within the room brew a draught that could kill a dragon.

"Professor." Hermione's gaze didn't rise above his chin. "How are Nott and Yaxley?"

"Shaken and exhausted. They ran laps while casting the strongest curses they knew." His mouth thinned. If Hogwarts had a proper Dark Arts class the young wizards would have been significantly better prepared to face a Dementor. "The creature has been repelled." Albus was reinforcing the wards of the Castle and sending his bitiest owl to the Ministry, not that Fudge would heed it. "I will return you to your House now."

Hermione had expected an interrogation. She was suspicious Snape wasn't more suspicious, but even with ten years acquaintance she couldn't read him. So she went quietly and tucked herself into bed in her empty dorm. Staring at the green and silver canopy above her, Hermione wondered whether Cathal would've gone for help. How could she know? The girl was just a skin she carried around; a mask to hide behind.

With the exception of the orphan Cathal, all the Slytherins who had stayed at Hogwarts over the Yule holidays wrote to their parents about the Dementor loose in the dungeons. Hermione knew this because her Housemates showed her the various replies, including the one from Hardrada Harper who had stabbed her quill into the parchment so vigorously she had torn the sheet in several places. Nett result: pabulum from Fudge.

When she told Marcus and the other older Slytherins who had invited themselves to their study sessions, he grimaced and said the response was typical. Fudge didn't move on an issue unless he feared for his job. Sirius Black running amok was a far more incendiary problem than a 'minor security incident' at Hogwarts, which the Minister blamed on Dumbledore's inattention.

The Snakes were ensconced in the library at one of the large tables near the Ancient Runes section, which was primarily the domain of older Years as the subject was a challenging elective. Bole was turning a book around in his hands looking at a Transfiguration diagram from several different angles hoping to figure out where to start. Flint had rocked back in his chair to read with his feet on the table because he hated knocking his shins on the stretcher beneath. Hearne, a Fifth Year desperate not to fail Charms, slid his essay across to Rosier and cradled his head in his hands.

Hermione felt an unexpected sense of comradeship with the fraught boy whose father demanded he get an OWL in a subject in which he, impartially, had little talent. The pure-blood emphasis on heritage rather than ability had left many of its scions struggling not to be relegated. A student doing sufficiently poorly in multiple subjects could be asked to leave the school before their OWLs, which was utter disgrace among the old families.

She was eighteen inches into Hearne's essay when she noticed how quiet the Library was. It struck her that Gryffindor was playing Ravenclaw, and that Flint wasn't dressed as a Dementor. Hermione paused trying to remember exactly when Malfoy, Crabbe, Goyle, and the Seventh Year had pranked Harry. It had definitely been the Ravenclaw match.

"You're missing Quidditch." She spoke before her underdeveloped cunning could stop her.

"Yeah." Flint agreed, flicking a page irritably. "But I've nearly got a handle on Quintessence and if I take a break I'll lose the plot." He scribbled a page number on a scrap bit of parchment he was using for his references. "Flitwick's remedial class is bloody useful. I'd be Stupefied without it."

A little thing, barely a tweak. It could be nothing. From what she knew of temporal magic, not every change was significant. You could step on a flight of butterflies and not alter the future. She didn't know what Flint did during the war. She'd never heard him mentioned as a Death Eater. And she couldn't, short of locking herself in a cellar for years, not affect time.

So why was her heart racing?

"Are you planning to go professional?" Hermione asked to say something to fend off her burgeoning panic attack. Flint shrugged and returned to reading. She did the same then shifted next to Hearne so she could quietly discuss how he could refine his essay. If he noticed how tense she was, he didn't say. He was at least as taut, his hands fidgeting with his quill.

News of the Gryffindor victory percolated into the Library via smiles on the red ties and frowns on the blue. Oliver Wood sauntered in late, making sure to grin broadly at the table of Slytherins. Flint glared back, muttering about doing something very uncomfortable to the Gryffindor Captain with his own broomstick.

The joie de vivre was short lived. The presence of the Dementors sapped everyone. The younger Years cried in private nooks and the older Years slogged grimly onwards as though the exams were the Gotterdammerung. Hermione kept to her terse habit and hoped no one noticed she wasn't as wearily miserable as her fellows. Her confidence in her fakery was shaken by Professor Lupin's guarded expression when she asked to be excused from the Boggart lesson.

She had arrived early to the special group class and made a show of taking interest in the rattling wardrobe. Remus watched her while trying to pretend he wasn't. He was thinking, she recognised his contemplative expression. Regrettably, when she walked up to him to ask to be excused from the class, he blanked his face. He wasn't the accomplished liar Snape was but hiding his lycanthropy had taught him self-control.

Professor Lupin agreed without cavil. Hermione felt his gaze on her all the way out of the classroom. Something was bothering him about Cathal Rosier. She didn't know what. Tucking herself away in her hidden laboratory, Hermione fussed around with a distillation still and worried. There was something, wasn't there? Or was Remus just angry over the implied extortion?

"Moppet, if you're available, could you come here?" She asked the walls. "It's not urgent."

The house elf appeared after a few minutes during which Hermione strained nettles to keep her hands busy. She was making progress with the testing and expected by the end of the year she would have some useful data. The next step would be finding whether any of the nettle species she had tested mixed well with any of the gel media she would like to use. Liquids were easier to brew but didn't last as long on the shelf.

"Miss wants Moppet not right away?" Moppet quirked her ears, interested in the not-summons. Her witch friend didn't like to bother her and never asked her to pick up things so she was puzzled by the at whim call.

"I'm probably being paranoid. Walking around the dungeons alone has given me too much time to over-think." Hermione explained in case she sounded daft for asking her question. "Has Professor Lupin talked about Cathal?"

"I heard Professor the Wolf talking to Professor the Cat over teacups." After some thought, Moppet provided this titbit. "They wasn't talking about just you. They was talking about all the Slytherins. He said you reminded him of your father. She said yes."

"I don't imagine they liked Evan Rosier much." There was no special reason why Remus shouldn't talk to Professor McGonagall. "Is that all they said?"

"The Professors looked unhappy. Headmistress Professor was all pinch-mouth." The house elf mimicked the Scottish witch's dour expression. "She said there were always some that went Dark. Then they talked about Malfoy. Professor the Wolf said he reminded him of his father too."

"I am really starting to see the appeal of Legilimency. I'd feel a lot more assured about my lies if I could be certain people believed them." Hermione heard herself whine and sighed. "Thanks, Moppet. I'm sorry to bother you. Professor Lupin looked at me oddly. I'm never sure I'm doing this Slytherin thing right."

"Can Miss do less right than idiot Crabbe and idiot Goyle?" Moppet asked with another twitch of her ears. Hermione laughed.

"You make a good point." She smiled for the first time in what felt like an eternity. "They do set the bar very low."