Grimmauld Place in December smelled like old magic and furniture polish and the particular staleness of a house that took itself very seriously.
Mia stood in the entrance hall and looked up at the row of mounted house-elf heads and thought, not for the first time, that pureblood interior decorating was a world unto itself.
"Stop," Bellatrix said quietly, appearing at her elbow.
"I wasn't going to say anything."
"You have your saying-something face."
"I have a neutral expression."
"You have approximately four expressions and none of them are neutral." Bellatrix steered her forward with a hand at her back, warm and brief. "Smile at my aunt when you meet her. Not warmly."
"What does warmly look like to Walburga Black."
"Suspicious."
"What does cool look like."
"Appropriate." A pause. "There's a narrow window. You'll find it."
Mia glanced sideways at her. Bellatrix was wearing the face she wore for her family — composed, controlled, every edge accounted for. But underneath it, just barely, was something Mia had learned to spot over months of paying attention. The faint tension around her eyes. The way she held herself like she was already tired and they'd been here four minutes.
She wanted badly to take her hand.
She didn't. Not here, not yet, not until the whole house understood the shape of things.
Soon, she reminded herself.
She followed Bellatrix into the drawing room and smiled at Walburga Black at exactly the right temperature.
Dinner was loud in the way that quiet families are loud — no one raised their voice, but the table hummed with about eleven separate undercurrents and Mia spent most of it mapping them while appearing to be entirely focused on her food.
Rodolphus was there. Of course he was. He sat four seats down and was well-behaved and looked at Mia occasionally with the patient, measuring expression of someone who had decided that patience was currently his best tool.
She looked back pleasantly and thought about the Vault collapsing around him and felt fine.
Alphard Black, on her left, was quietly hilarious — he made two comments under his breath during the soup course that made her genuinely struggle not to laugh, and she decided she liked him immensely.
Narcissa, across the table, watched Mia with her usual comprehensive attention, and at some point during the main course passed her the salt without being asked, which from Narcissa was practically a declaration of loyalty.
Bellatrix was at the other end of the table, engaged with her father. She didn't look at Mia directly — they'd agreed on that, too obvious, Rodolphus would clock it instantly — but twice during the meal her eyes moved down the table for just a second, checking, the way you check on something you care about without wanting anyone to know you care about it.
Mia looked at her plate and hid a smile.
The family dispersed after dinner in various directions and Mia was considering the library when Bellatrix appeared at her shoulder.
"Come with me," she said quietly. "And look like you're going to bed."
"Where are we actually going."
"The archive."
Mia looked at her. "The private archive."
"My grandfather's private archive, yes." She was already moving toward the stairs, unhurried, nobody's-sneaking-anywhere. "There's something in it I've been trying to get to for two years. He keeps it warded but the wards reset at midnight and there's a twenty minute window."
"What's in it."
"I'll tell you when we're inside." She glanced back, eyes bright. "Try not to look excited."
"I'm not excited."
"You're extremely excited."
Mia was, in fact, extremely excited. She followed Bellatrix upstairs and said nothing.
The archive was on the third floor behind a door that looked like a wall.
Bellatrix stood in front of it with her wand, working through a sequence of dismantling charms with the focused efficiency of someone who had been planning this for a while. Her lips moved slightly. Her hands were steady.
Mia watched her work. There was something about Bellatrix doing magic that she never quite got used to — the quality of it, the precision, the way her whole self went into it and nothing was wasted. It wasn't like watching anyone else cast.
"Stop watching me," Bellatrix said, without turning around.
"I'm monitoring for complications."
"You're watching me."
"Both things can be true."
The door clicked and swung inward. Bellatrix looked back with an expression that was trying not to be pleased with itself and failing slightly. Mia grinned at her. Bellatrix turned back to the archive.
"Twenty minutes," she said. "Don't touch anything without telling me first."
They slipped inside.
The archive was smaller than Mia had expected and more extraordinary.
Floor to ceiling shelves, packed with documents and ledgers and objects she couldn't immediately identify — sealed glass cases, rolled maps, stacked folios in cracked leather bindings. Everything organised in the particular way of someone who had been collecting for a very long time and had their own system that would be illegible to anyone else.
It smelled like old parchment and something sharper underneath. Concentrated magic, layered and old, the smell of documents that had been handling secrets for generations.
"What are we looking for," Mia said quietly.
"Third shelf from the top, east wall. Black family correspondence from the 1940s." Bellatrix was already moving, pulling a thin wooden ladder along its rail. "There are letters — my grandfather received them from a source inside Borgin and Burkes. Around 1945."
Mia went still. "Borgin and Burkes in 1945."
"Yes."
"That's when Voldemort was working there."
"That's when Tom Riddle was working there," Bellatrix said. "Before anyone knew what he was going to be." She climbed the ladder with easy, practiced balance, her wand lighting the way. "My grandfather was paying attention to him. I think he knew something — about what he was doing there, what he was looking for. The correspondence was sealed before I was old enough to access it." She reached the third shelf and began moving carefully through the documents. "Here."
She came back down with a folio, old and dark with handling, and spread it on the small reading table in the centre of the room.
They leaned over it together, Bellatrix's shoulder warm against hers.
The letters were cramped and careful, written in a hand that was meticulously controlled. Arcturus's responses were clipped and precise. The source — identified only by initials, A.B., which meant nothing immediately — wrote about a young man at the shop. Brilliant. Strange. Asking questions about objects with particular histories. Paying for information about very specific things.
"Heirlooms," Mia said, reading. "He's asking about heirlooms."
"Family heirlooms specifically. Objects with long histories, strong magical signatures." Bellatrix turned a page. Her voice had dropped, the way it did when something had her full attention. "He was looking for Horcrux vessels. Even then."
"He would have been — sixteen, seventeen." Mia did the calculation. "He was already planning it."
"He was always already planning it." Bellatrix turned another page and then stopped.
Mia looked at what she'd found.
It was a list. Handwritten, in a different hand from the letters — younger, less controlled, the writing of someone who didn't yet know how to make their hand unreadable. Seven items. The first three had notations beside them. The fourth had a question mark.
"He made a list," Mia said.
"He made a list," Bellatrix said. "And my grandfather had a copy of it." She sat back. Something moved across her face — not fear, something more complex than fear. "Mia. If we know what he chose—"
"We know what to look for." Mia's heart was going fast. "We can find them before he makes them. Before they exist."
"Some of them will already exist. He started in his sixth year at Hogwarts, there's documented evidence—"
"The diary," Mia said. "The diary already exists. We need to find—"
"The ring," Bellatrix said, pointing at the second item on the list. "Gaunt family ring. He notes it specifically."
"The locket. Slytherin's locket." Mia pointed at the third. "I know where that ends up. I know where most of these end up. Bellatrix—" She looked up. They were six inches apart in the small amber light of the archive, both breathing faster than usual, the list between them. "This changes everything."
Bellatrix looked at her.
Then she laughed — sudden and real, the full version, head tipping back. It filled the small room.
"What," Mia said, smiling before she knew why.
"We broke into my grandfather's archive at midnight on Christmas Eve," Bellatrix said, "and found a list of Voldemort's Horcruxes."
"Yes."
"On Christmas Eve."
"That's when the window was."
"I know that's when the window was." She shook her head, still smiling. "Only you. Only with you would I be doing this."
"You were doing this before I arrived," Mia said. "You've been trying to get in here for two years."
"Yes but I would have been alone and considerably less pleased about it." Bellatrix looked at her for a moment, the smile still there, warm and unguarded in a way she almost never was outside of private rooms. "We need to copy the list."
"Already on it." Mia had her own wand out, copying the document with a careful transcription charm. "Fourteen minutes left."
"Efficient."
"Always."
Bellatrix leaned over her shoulder to check the copy, close enough that Mia could feel her breath against her cheek, and said nothing for a moment.
"After the holidays," she said quietly. "We start on this properly."
"We start on this properly," Mia agreed.
Bellatrix's hand came to rest briefly at the small of her back — warm and steady and gone again before it could mean anything in a room with no one watching.
Except it meant everything. It always did.
They were back in the corridor with three minutes to spare.
Bellatrix sealed the archive behind them with the same sequence in reverse, checked the wards had reset, and pocketed her wand. Then she leaned back against the wall and looked at Mia in the dark corridor with the particular expression she saved for moments nobody else got to see.
"Good Christmas so far," Mia said.
"It has improved significantly since dinner."
"Alphard is funny."
"He's the only tolerable one at the table." She paused. "Narcissa passed you the salt."
"I noticed."
"She likes you." Said as though this was a mildly surprising development Bellatrix had already come to terms with. "She doesn't usually like people."
"Black women seem to have that in common."
Bellatrix looked at her. "Are you including me in that."
"I'm including you most of all." Mia held her gaze. "You like me extremely and it took you most of the summer to admit it."
"It took me a reasonable amount of time to confirm what I already knew," Bellatrix said, which was such a Bellatrix thing to say that Mia laughed, and then Bellatrix smiled properly and the corridor was cold and dark and completely empty and Mia stopped thinking about being careful.
She stepped forward and kissed her.
Bellatrix made a small sound of surprise — she always did, every time, as if she was perpetually slightly caught off guard by the fact of it even now — and then kissed her back with both hands in Mia's hair and all the careful management gone.
For a minute the Horcrux list and Rodolphus and Walburga and the whole complicated architecture of this house didn't exist at all.
Then a door opened somewhere below them and they separated quickly, both slightly breathless, listening.
Silence. Someone going to the kitchen. Nothing more.
Bellatrix straightened her robes with great dignity. Mia pressed her lips together to keep from laughing.
"Bed," Bellatrix said.
"Yes."
"Separate beds."
"I know."
"In separate rooms."
"Bellatrix."
"I'm establishing clarity."
"You're very flustered."
"I am not—" She stopped. The expression on her face was genuinely indignant and completely undermined by the fact that her hair was slightly dishevelled. "Go to bed, Mia."
"Goodnight," Mia said sweetly, and went.
She walked down the corridor to the guest room and lay in the dark with the copied list in her robes and the feeling of Bellatrix's hands still in her hair and thought that she had come back through time to save the world.
She was starting to think the world was mostly an excuse.
They spent Christmas morning in the library.
Not secretly — Bellatrix simply appeared at breakfast, said we'll be in the library to the room at large in the tone that didn't invite questions, and that was that. Her family had apparently learned, over seventeen years, that Bellatrix in a library was both inevitable and non-negotiable.
They spread the Horcrux list between them and worked.
Mia knew more than Bellatrix — she had lived through the Horcrux hunt, had held two of them, had watched one destroyed. She talked Bellatrix through everything she knew while Bellatrix cross-referenced against her own considerable knowledge of Dark magic and took notes in her sharp, slanted hand.
The ring — Gaunt family heirloom, somewhere in Little Hangleton.
The locket — Slytherin's locket, would eventually end up with Mundungus Fletcher, but they had years before that.
The cup — Hufflepuff's cup. Mia knew where it ended up. She kept that information very controlled in her expression.
"The cup ends up somewhere specific," Bellatrix said, without looking up.
"Yes."
"Somewhere you know."
"Yes."
A pause. Bellatrix looked up. "In my vault."
"In your vault," Mia confirmed.
Something moved across Bellatrix's face. Not hurt exactly — more like the particular grimness of someone receiving confirmation of something they'd already suspected. "He put it there through me."
"Through the version of you that existed in my timeline, yes." Mia held her gaze. "He used people he thought were loyal. He thought your loyalty was to him."
"It will not be," Bellatrix said flatly.
"I know."
"I want that one specifically," she said. "When we find them. I want to be the one who destroys the cup."
"Done," Mia said simply.
Bellatrix looked at her for a moment. Then she looked back at her notes. "What about the seventh? The list only has notations for six."
"The seventh was unintentional." Mia paused. "It was Harry."
Bellatrix stared at her. "The boy—"
"Was a Horcrux. Yes. He had to die to destroy it." She kept her voice even. "He came back. It's complicated."
Bellatrix sat back and looked at the ceiling. "It is always, with you, more complicated than the sentence suggests."
"That's an accurate observation."
She dropped her gaze back to the notes. "So seven Horcruxes. We know the location of three. Approximately."
"Approximately."
"And we have—" She calculated. "Years before he completes them. Before he has the power to begin the war properly."
"Years," Mia agreed. "If we move carefully."
Bellatrix was quiet for a moment. Outside the library door, somewhere in the house, someone was playing the Wizarding Wireless at low volume. A log shifted in the fire. The morning was grey and cold through the tall windows.
"We're going to find them all," Bellatrix said.
Not a plan. Not a question. Just a fact she was deciding, out loud, the way she decided everything.
"Yes," Mia said. "We are."
Bellatrix picked up her quill. Mia picked up her copy of the list. The fire crackled. Outside London was cold and grey and somewhere out there a young man named Tom Riddle had no idea that two girls in a library on Christmas morning had just decided to take everything from him.
The rest of Christmas passed in the way Christmas does when you'd rather be somewhere else — slowly, and then all at once.
Rodolphus was navigated. Walburga's genealogy interrogation was survived — Mia answered every question correctly and Bellatrix watched from the settee with an expression of studied indifference that Mia had come to recognise as proud. Narcissa found them in the library on the second day and sat down without asking and stayed for two hours, at first pretending to read and then actually reading and then asking questions that were sharp enough that Bellatrix looked up from her own work twice.
On the last night Alphard found Mia alone in the hallway and said, very quietly, whatever you're doing, it's working, and then wandered off without elaborating, which she decided was the most meaningful compliment she'd received all Christmas.
They left on the twenty-seventh, back to Hogwarts, back to the quiet of term not yet started, and the moment they were through the gates Bellatrix took her hand.
Just that. No words. Just her hand, warm and certain, and the castle rising ahead of them through the winter dark.
"Next term," Bellatrix said.
"Next term," Mia confirmed.
"We start properly."
"We start properly."
They walked up to the castle together in the cold and the quiet, the Horcrux list in Mia's robes, the future somewhere ahead of them, still rewritable.
The castle was a ghost of itself, empty and echoing in the week between Christmas and New Year’s.
Their footsteps on the stone were the only sound in the Entrance Hall. The torches flickered low. The Christmas tree in the corner was still up, but the enchantments had dimmed, leaving it a silent, dark shape in the gloom.
Bellatrix didn’t let go of her hand as they climbed the stairs toward the dungeons. Her grip was firm, a brand against Mia’s skin.
“The others won’t be back until the thirtieth,” Bellatrix said, her voice a low murmur that bounced off the cold walls.
“Just us,” Mia replied.
“Just us.”
The Slytherin common room was a cavern of greenish light and deep shadows. The fire in the grate was embers. Bellatrix flicked her wand and it roared to life, casting long, dancing shapes across the low ceilings.
She finally released Mia’s hand to shrug off her traveling cloak, tossing it carelessly over the back of a leather sofa. She stood by the fire, her profile sharp in the sudden light.
Mia watched her. The way the fire caught the wildness of her curls, the tense line of her shoulders beneath the fine wool of her dress. The quiet here was different from the tense quiet of Grimmauld Place. It was theirs.
“I hate that house,” Bellatrix said, not looking at her. “Every time. I always forget how much until I’m back in it.”
“You handled it.”
“I perform it.” Bellatrix turned then, her black eyes reflecting the flames. “There’s a difference.”
Mia moved to stand beside her, close enough to feel the heat from the fire, and from her. “I know.”
“Do you?” Bellatrix’s gaze was searching, intense. “Your performance is flawless. The perfect pureblood heiress. It’s unnerving.”
“It’s necessary.”
“I know that.” A faint, sharp smile touched her lips. “I’m not criticizing. I’m admiring.”
Bellatrix reached out then, not for her hand, but to trace the line of Mia’s jaw with her fingertips. The touch was light, almost speculative. Mia’s breath caught.
“You’re real here,” Bellatrix murmured. “With me. Not performing.”
“Always,” Mia said, the word coming out rough.
Bellatrix’s fingers slid back, into her hair, gripping gently. She pulled Mia in, not for a kiss, but to rest their foreheads together. Her eyes were close, dark pools Mia could drown in.
“Tell me something real,” Bellatrix whispered. “Not about the war. Not about the list. Something from before. From you.”
Mia swallowed. The request was a vulnerability she hadn’t expected. Bellatrix was asking for Hermione, not Mia.
“I used to get books for Christmas,” Mia said softly. “Every year. My parents would wrap them. I could always tell by the shape.”
Bellatrix’s thumb stroked her temple. “What kind of books?”
“Anything. Everything. Once, a set on advanced arithmancy that was far too old for me. I stayed up all night trying to decipher it.”
“Of course you did.” Bellatrix’s voice was warm. “And your parents?”
“They were dentists. They fixed teeth.” Mia felt a familiar, distant ache. “They thought magic was wonderful. They never understood the cost.”
Bellatrix was quiet for a moment. Then she said, “I used to steal books from my father’s study. He never noticed. Or he pretended not to.”
“What kind of books?”
“The dark ones. The ones with locks.” Bellatrix’s smile was a slash of white in the firelight. “I picked the locks with a hairpin. Took me weeks to learn the spell for the silencing charm so the pages wouldn’t whisper when I turned them.”
Mia laughed, a quiet, surprised sound. “You were a menace.”
“I was curious.” Bellatrix’s grip in her hair tightened, just slightly. “I still am.”
She closed the last inch between them and kissed her.
It was different from the frantic kiss in the Grimmauld corridor. This was slow, deep, an exploration. Bellatrix’s mouth was warm and insistent, tasting of peppermint tea and the cold outside. Mia sank into it, her hands coming up to cradle Bellatrix’s face.
Bellatrix made a low sound in her throat and walked her backward, step by step, until Mia’s shoulders met the cold stone wall beside the fireplace. She pressed into her, all lean muscle and heat, one hand still tangled in Mia’s hair, the other sliding down to her hip.
“You feel that?” Bellatrix breathed against her mouth.
Mia could feel everything. The hard line of Bellatrix’s body against hers. The rapid beat of her own heart. The slow, slick heat building between her legs. “Yes.”
“Good.”
Bellatrix kissed her again, deeper, her tongue sweeping into Mia’s mouth. Her hand on Mia’s hip slid around to the small of her back, pulling her closer, grinding their hips together in a slow, deliberate circle.
A gasp tore from Mia’s throat. Pleasure, sharp and sweet, sparked up her spine. She could feel the hard ridge of Bellatrix’s thigh through her skirt, the pressure exactly where she needed it.
Bellatrix broke the kiss to trail her mouth along Mia’s jaw, down the column of her throat. Her teeth scraped lightly over Mia’s pulse point, and Mia’s head fell back against the stone with a soft thud.
“Bella—”
“Shhh.” Bellatrix’s breath was hot against her skin. “Just feel it.”
Her hand moved from Mia’s back, sliding around her hip again, then up under her sweater. Her palm was searing against Mia’s stomach. Mia trembled.
Bellatrix’s fingers found the waistband of her trousers. She didn’t undo the button. Just hooked her fingers there, possessive and still.
“Tell me you want this,” Bellatrix whispered, her lips brushing the shell of Mia’s ear.
“I want this.” Mia’s voice was barely audible.
“Tell me you want me.”
Mia turned her head, caught Bellatrix’s gaze. Her eyes were black fire. “I want you. I have never not wanted you.”
Something raw and triumphant flashed across Bellatrix’s face. She kissed her again, hard, and her hand finally moved, popping the button open, sliding the zipper down.
The cold air hit Mia’s stomach. Then Bellatrix’s hand was there, her fingers slipping beneath the lace of her knickers, and Mia’s world narrowed to that touch.
Bellatrix didn’t rush. Her fingers traced through the wet heat, learning her, making Mia shudder and press into her hand. A low, broken sound escaped Mia’s lips.
“You’re so wet,” Bellatrix murmured, her own breath coming faster now. “For me.”
“Always for you.”
Bellatrix kissed her, swallowing her next gasp as her fingers finally, perfectly, slid inside.
Mia cried out into her mouth. The stretch, the fullness, the rightness of it stole the air from her lungs. Bellatrix’s thumb found her clit, circling with a pressure that made stars burst behind Mia’s eyelids.
“Look at me,” Bellatrix breathed.
Mia forced her eyes open. Bellatrix was watching her, her expression fierce, open, utterly captivated. Her fingers moved, slow and deep, setting a rhythm that had Mia’s hips rocking against her hand.
“That’s it,” Bellatrix whispered. Her forehead was damp, a curl stuck to her temple. “Let me feel you.”
Mia was close. The tension coiled tight in her belly, her thighs trembling. She could feel every shift of Bellatrix’s fingers, every brush of her thumb. The fire crackled. The castle was silent. There was only this.
“Bella, I’m—”
“I know.” Bellatrix’s voice was rough with want. “Come for me.”
She crooked her fingers, and Mia shattered.
The orgasm rolled through her in waves, pulling a ragged sob from her throat. Bellatrix held her through it, her body a solid anchor against the stone, her fingers working her gently until the last tremor subsided.
Mia slumped against her, boneless, her face buried in Bellatrix’s neck. She could feel Bellatrix’s heart hammering against her own chest.
Bellatrix slowly withdrew her hand, bringing it up to cradle the back of Mia’s head instead. She held her there, breathing hard, her lips pressed to Mia’s hair.
“I have you,” Bellatrix whispered, the words a vow in the dark.
Mia believed her.