The N.E.W.T.s arrived the way all inevitable things arrived — with considerably less warning than felt reasonable given how long they'd been coming.
The castle in the final weeks of term had a specific quality that Mia remembered from the first time around — a compressed, slightly frantic energy, the library perpetually full, the corridors quieter than usual, people moving with the focused tunnel vision of seven years converging into three weeks of examinations.
Bellatrix found it faintly ridiculous.
Not the exams themselves — she took those seriously in the way she took everything seriously, which was completely and without apology. What she found ridiculous was the collective panic of people who had had seven years to prepare and were only now discovering that preparation mattered.
"The third year Ravenclaw in the library corner has been crying for four days," she said one morning over breakfast.
"She's sitting her O.W.L.s," Mia said. "That's different."
"It's still four days."
"Not everyone has your relationship with academic pressure."
"My relationship with academic pressure is perfectly normal."
Mia looked at her.
"It's functional," Bellatrix amended.
"You revised your N.E.W.T. curriculum in its entirety in October," Mia said. "As a warmup. Before we started the actual work."
"That's called preparation."
"That's called being you." Mia stole a piece of her toast. "Which is not a criticism. I benefit from it constantly."
Bellatrix allowed this. "How are you feeling about the Transfiguration practical."
"Fine. You made me do it wandlessly last week which means the wand version feels effortless."
"That was the point." She opened her notes — because Bellatrix always had notes at breakfast, which Mia had long since stopped commenting on. "Potions theory paper is Monday. You should review the Golpalott's Third Law applications—"
"I've reviewed them."
"The specific applications to complex antidotes—"
"Bellatrix. I know Potions."
"You know it well. I want you to know it perfectly."
Mia looked at her across the breakfast table — the notes, the focused expression, the particular quality of someone whose version of caring about you included making absolutely certain you were as prepared as it was possible to be.
"I know it perfectly," she said, softer.
Bellatrix looked up. Read her face. The noteslosed fractionally. "Good," she said.
The first exam was Charms.
Mia sat in the Great Hall with her quill and her wand and the particular calm that had become her default register — not the performed calm of someone managing nerves, just actual calm, the equanimity of someone who had survived things that made a Charms N.E.W.T. feel like a warm morning.
She finished forty minutes before the time and spent the remaining time checking her work twice and then watching the room.
Bellatrix was four rows ahead and to the left. Her quill moved with the even pace of someone who had no doubt about any answer and was simply transcribing what she already knew. Her posture was perfect. She didn't fidget. She didn't look up.
She was the first to put her quill down.
They worked through the exam period with the rhythm they'd built over the year — training at six, exams through the day, work in the evenings on the Horcrux research and the joint casting practice and Mia's Occlumency, which was improving steadily and was now holding against Bellatrix's attempts for an average of twelve minutes.
Not enough.
Not yet.
But twelve minutes was not nothing.
"Longer," Bellatrix said, one morning after a session. Not critical. Just the standard she was holding.
"I know," Mia said.
"You're letting it slip at the edges. The surface is solid in the centre but the peripheral—"
"I know. It happens when I get tired."
"Which is exactly when someone will try to use it against you." She handed Mia a glass of water. "The answer isn't to not get tired. It's to practice tired."
"We're practicing at six in the morning."
"You're not tired at six. You're annoyed." The corner of her mouth moved. "Different thing."
Mia looked at her. "When do you suggest we practice tired."
"After the Potions practical. You'll be genuinely exhausted after four hours of brewing." She met her eyes. "That's when we test it."
"You want to attempt Legilimency on me immediately after a four hour Potions exam."
"Yes."
"That's either very good training methodology or slightly sadistic."
"It's both," Bellatrix said pleasantly. "Those things aren't mutually exclusive."
The Potions practical was four hours and Mia was genuinely exhausted after it.
Bellatrix was waiting in the fourth floor classroom looking entirely fresh, which was either impressive or deeply unfair depending on how you looked at it.
"You don't have to look so well-rested," Mia said.
"I'm not doing anything with my face."
"Your face is naturally smug."
"My face is naturally composed." She raised her wand. "Ready?"
"Give me thirty seconds."
"Twenty."
Mia sat down on the edge of a desk and found her surface — the text she'd been using, a passage from a Transfiguration theory text she'd memorised in October, clean and factual and completely emotionally neutral. She built it up in the front of her mind and let everything else fall back.
"Ready," she said.
Bellatrix entered.
The pressure was familiar now — that inside-observation quality, the presence that was not-her moving along the surface of her thoughts. She felt it probe at the edges, looking for a catch, and she held the text and kept the surface smooth and didn't push back.
A minute. Two. The tiredness made it harder — she could feel the surface wanting to soften, the memories pressing up against it from underneath.
The Department of Mysteries rose. She pushed it back.
The field in August rain tried to surface. She held the text and let it stay underneath.
Three minutes.
Four.
At four minutes thirty Bellatrix withdrew.
"Well?" Mia said.
"Four minutes thirty-seven seconds." Bellatrix lowered her wand. The professional expression had something underneath it. "Tired, post-exam, and you held it nearly five minutes." She paused. "That's — significant progress."
"How significant."
"Three weeks ago you couldn't hold it thirty seconds." She looked at her steadily. "You're learning faster than anyone I've tried to teach."
"You've tried to teach Occlumency before?"
"Once. Fifth year. Narcissa asked me to show her the basics." She paused. "She lasted four seconds and then burst into tears, which I feel obliged to mention was not my fault."
Mia laughed despite herself. "Poor Narcissa."
"She's fine. She avoided the practice entirely and developed a naturally composed exterior instead, which is a different kind of defence." Bellatrix almost smiled. "Actually more useful socially."
"But less useful against Voldemort."
"Considerably less useful against Voldemort." She lowered herself to sit beside Mia on the desk edge, close enough that their shoulders touched. "You'll be at ten minutes by the end of the summer."
"Is ten minutes enough."
Honest answer from Bellatrix, which meant she considered it before speaking. "Against most Legilimens, yes. Against Voldemort—" She paused. "We won't be in his mind long enough for it to matter. The Occlumency is a precaution, not a primary defence."
"The primary defence is being fast enough."
"The primary defence is being smart enough." She looked at her sideways. "Which you are. Consistently."
"High praise."
"It's accurate." She stood up. "Defence Against the Dark Arts practical tomorrow. We should run the counter-curse sequence tonight."
"Tonight I am sleeping," Mia said.
"After the counter-curse sequence."
"Bellatrix."
"Twenty minutes. Just the sequence."
Mia looked at her ceiling. "Fine. Twenty minutes."
"Thirty."
"You said—"
"I said twenty. I meant thirty." She held the door open. "Come on."
The Defence Against the Dark Arts practical was the last exam.
Mia walked out of it into the June afternoon with the specific lightness of something enormous being finished and stood in the courtyard with her face in the sun for thirty seconds before Bellatrix appeared beside her.
"Well?" Bellatrix said.
"I may have slightly shown off in the practical component."
"Define slightly."
"The examiner asked me to demonstrate a shielding charm and I did the wandless version."
Bellatrix looked at her. "The wandless version you learned four weeks ago."
"It seemed relevant."
"What did the examiner say."
"He wrote something down for a long time." Mia paused. "In a good way, I think."
Bellatrix looked at her with the expression that was trying not to be pleased and wasn't succeeding. "You're insufferable," she said.
"I learned from someone."
"I have never once shown off in an exam."
"You finished the Charms written paper forty minutes early and then visibly had to stop yourself from redoing it for fun."
"That's not showing off. That's—"
"Being you." Mia bumped her shoulder. "Which I've already established is not a criticism."
Bellatrix made a sound that was almost a laugh. The June light was warm and the courtyard was filling up with other students emerging from the exam with the dazed relief of people returning from somewhere difficult and the summer was right there, immediate and open and full of things that needed doing.
Avery found them twenty minutes later.
"Done," he said, appearing from the direction of the Great Hall with his robes slightly dishevelled and the expression of someone who had just delivered a very long performance and was finished with it.
"How was it," Mia said.
"The Dark object identification section was either brilliant or terrible and I won't know which until results." He paused. "I may have identified a cursed object using methodology I learned in this school year that isn't technically on the curriculum."
"That was in the exam?" Bellatrix said.
"They had a real one." He looked at her. "I assume that's your influence somehow."
"I have no influence over N.E.W.T. examination content."
"You have influence over everything in this school," Avery said, without rancour. "It's just a fact." He looked between them. "When do we leave."
"Tomorrow morning," Bellatrix said. "The Express at eleven."
"And the summer."
"The summer," Mia said, "is when the work gets serious."
He nodded. Not daunted. Just acknowledging the shape of what was ahead. "Good," he said simply. "I'm ready for serious."
He wandered off toward the Slytherin common room and Mia and Bellatrix stood in the courtyard in the June light.
The last night at Hogwarts had its own particular quality.
It wasn't sad exactly — they were leaving to do something, not leaving to nothing. But the castle had been the container for everything that had happened since August, the place where Mia Peverell had become real, where the plan had gone from theoretical to actual, and leaving it felt like the end of a first chapter. Which it was.
They went to the lake after dinner.
Not to work. Not to plan. Just to be there, which had become a thing they did — the lake at different times of year, carrying different weights, always somehow the right place.
It was warm for June in Scotland, the sky still light at nine o'clock, the water moving in the slight evening breeze. They sat in the grass where they'd sat in August and the year was between them, enormous and completed.
"Tell me something good," Mia said.
Bellatrix looked at her sideways. "What?"
"Something good. From this year. One thing."
Bellatrix looked at the water. Thinking, which she always did when something seemed simple and wasn't.
"The archive," she said finally. "Christmas Eve. Finding the list."
"That's your best memory from the year?"
"It's one of them." She paused. "You laughed. When I said it was Christmas Eve and we'd found a Horcrux list." She looked at the water. "You laughed like it was the best thing that had happened in a long time."
"It was," Mia said.
"I know." Quiet. "That's why it's the memory."
Mia looked at her profile in the evening light.
"Your turn," Bellatrix said.
"The bookshop," Mia said. "In Hogsmeade. In February."
Bellatrix looked at her.
"You looked at that book in the window and you couldn't help yourself," Mia said. "You've never once in your life wanted something simple just for the wanting of it. And you wanted that book just because it was interesting and it was there." She paused. "I liked seeing that."
Bellatrix was quiet for a moment. "You bought it for me."
"I know."
"You didn't have to."
"I wanted to." She looked at the water. "That's allowed."
Bellatrix didn't say anything for a moment. The lake moved. The light was going slowly, the sky shifting from blue to something warmer at the edges.
"I have the book," Bellatrix said. "It's packed."
"Good."
"I've read it twice."
"I know. You annotated it." Mia smiled. "I may have looked."
"You went through my annotations?"
"Only the first chapter." She paused. "You wrote correct but incomplete next to the author's central thesis."
"It is correct but incomplete."
"I know. That's why I liked it." She looked at her. "You argue with books. Alone. In your room. At midnight."
"I engage critically with—"
"You argue with books." Mia leaned into her slightly. "It's one of my favourite things about you."
Bellatrix looked at her for a moment with an expression that was unguarded and warm and slightly helpless, the expression of someone who had not anticipated being loved this specifically.
"We should go in," she said. "Early start tomorrow."
"Five more minutes."
A pause. "Five minutes."
They sat by the lake while the last of the light left the sky and the castle reflected in the water and somewhere across the grounds Sirius Black was being extremely loud about something that Mia chose not to investigate, and the summer was waiting past the edge of the year like a door standing open.
Five minutes became twenty.
Neither of them mentioned it.
The last morning.
Trunks in the corridor. The common room emptying. The particular noise of a school in transit — voices and footsteps and the sound of seven years being packed into cases and carried toward the stairs.
Narcissa found Mia in the corridor outside the dormitory.
She was composed and neat and her trunk was already at the bottom of the stairs and she looked at Mia with the clear assessing eyes that had been watching since September.
"You're not coming back," she said.
"No," Mia said. "Neither are you, technically — you've got two more years."
"I meant you're not coming back to school after this." She paused. "You're going somewhere else. Doing something else."
Mia looked at her. Thirteen years old, and already understanding more than she was supposed to. "Yes," she said.
"Is Bellatrix going with you."
"Yes."
Narcissa was quiet for a moment. "Is it dangerous."
Mia considered the truthful answer and its several components. "Yes," she said. "Some of it."
Narcissa absorbed this with the composure of someone who had been absorbing difficult information her whole life. "She'll be fine," she said. Not a comfort — a statement, the kind you make when you know the person you're talking about well enough to be certain.
"She will," Mia agreed.
Narcissa looked at her for another moment. Then she held out her hand.
Formal. Old-fashioned. Very Black.
Mia shook it.
"Write to me," Narcissa said. "Occasionally. I like knowing things."
"I'll write," Mia said.
Narcissa picked up her bag and walked toward the stairs with her usual immaculate composure and Mia watched her go and thought that in ten years she was going to be formidable in ways that the world was not adequately prepared for.
Andromeda was at the bottom of the stairs.
She didn't say much — she wasn't much for ceremony, Andromeda, which was one of the things that distinguished her from the rest of them. She just looked at Mia with those warm direct eyes and said "take care of her" in a tone that meant more than the words.
"Always," Mia said.
Andromeda nodded. Then, very briefly, she hugged her — quick and genuine, the kind of hug that doesn't need to be long to mean something.
Then she was gone, into the crowd, back to her own complicated world of careful secrets and Ted Tonks and everything she was building toward whether she knew it yet or not.
Sirius intercepted them on the platform.
He arrived at a run, slightly out of breath, with James Potter three steps behind him and the expression of someone who had been looking for them for twenty minutes.
"Right," he said. "You're leaving."
"That's generally what happens at the end of the year," Bellatrix said.
"You know what I mean." He looked at Mia first and then at Bellatrix and then back at Mia. "Whatever you're doing this summer. It's the actual thing, isn't it. Not prep. The thing itself."
Neither of them answered.
Sirius looked at Bellatrix. Something moved between them — the particular complicated frequency of family that had been broken and rebuilt into something different, not fixed exactly, not the same as before, but present. A wire stretched between them that neither of them had cut.
"Be careful," he said to her. Simple. Stripped of his usual performance.
Bellatrix looked at him for a moment.
"You too," she said.
He nodded. Then the grin came back — the wide, unstoppable one — and he clapped Mia on the arm and said "the suits of armour thing was the best night of my fifth year" and vanished back into the crowd with Potter and the particular chaotic energy of someone who made every room louder by being in it.
Bellatrix watched him go with an expression Mia had never quite seen on her before.
"He's going to be alright," Mia said quietly.
"He'd better be," Bellatrix said. Just that. But she meant it in the way she meant everything — completely and without reservation.
The Hogwarts Express pulled out of the station at eleven exactly.
They sat in a compartment with Avery — who had brought an unreasonable amount of food for a five hour journey and shared it without being asked, which Mia had decided was his primary love language — and watched Scotland slide past the windows, green and wide and full of itself.
The work was on the table between them. Not literally — no parchment, no notes, nothing that could be seen. But present in the way things are present when three people in a small space are all thinking about the same thing.
"The cup," Bellatrix said, at some point past Perth.
"The cup," Mia confirmed. "That's first."
Avery looked at Bellatrix. "Your vault."
"My vault," she said evenly. "Yes."
He looked at her for a moment with the consideration of someone who understood what that meant and wasn't going to make it larger than it needed to be. "Do you need me for that one."
"Yes," Bellatrix said. "But not for the extraction. For after."
"After."
"The cup's destruction is—" She paused. "Personal. I'd like backup for the approach and the aftermath. The actual moment—" She looked at Mia.
"Just us," Mia said.
He nodded. "Done."
The train moved south and the summer opened out ahead of them through the window, enormous and unwritten, and somewhere in it five more Horcruxes waited and Voldemort was writing patient letters and Rodolphus was recalibrating and the joint casting was getting stronger every week and the Occlumency was holding for twelve minutes and Voclain was in Edinburgh with a grey cat and a folder that had the final stage of something that might change everything.
Mia looked at Bellatrix beside her, reading — of course reading, she'd been reading since they crossed the border, the Transfiguration text she'd pulled from her bag with the ease of someone who had packed specifically for a five hour train journey.
"What are you reading," Mia said.
"Advanced Transfiguration theory. There's a chapter on molecular restructuring at the magical level that has implications for the soul fragment destruction sequence."
"You're doing Horcrux research on the Hogwarts Express."
"I'm doing adjacent research on the Hogwarts Express." She turned a page. "There's a difference."
"There really isn't."
"There's a—"
"I love you," Mia said.
Bellatrix stopped. Looked up from her book. The compartment was warm and Avery was very pointedly looking out the window and the Scottish countryside was giving way to something greener and flatter and the summer was right there.
"I love you too," Bellatrix said. The deliberate choice of it, as always. "Don't interrupt my reading."
"You'll finish it in forty minutes."
"Thirty-five." She looked back at the book. "Then you have my full attention."
"I'll time it."
"Please do." The corner of her mouth curved. "I'm faster when I have an audience."
Avery made a sound into the window that was suspiciously like a suppressed laugh.
Bellatrix turned a page.
Mia looked out the window at the summer coming and felt the ring warm on her finger and the plan solid in her chest and the year behind them and everything ahead of them and thought that she had come back through time to save the world.
She was saving it.
One Horcrux at a time, one morning training session at a time, one late night in a library at a time, one hand held across a table at a time.
It was, she decided, the best way she could possibly imagine doing it.