The first rule of the linked book was that it was not a toy.
Hermione wrote that rule.
Matthew did not argue with it.
That made everyone suspicious.
The linked book began because Hermione said, very calmly, that owls were inefficient.
This happened three days after Diagon Alley, when the school supplies had been sorted, labelled, indexed, checked against the list twice, and then checked again because Hermione had not trusted Matthew's definition of "sorted." The sitting room of the Knight house had become a small bookshop. Two sets of first-year texts sat on the table. Rune books occupied one chair. Warding books occupied another. Potion ingredient guides were stacked far away from the kitchen because Helen Granger had said she did not want anything called "dried spleen" within sight of dinner.
Matthew's expandable trunk sat open on the rug, larger inside than outside and already organising itself into compartments with a faint clicking sound that Hermione found fascinating and Daniel found personally offensive.
"It should not fit," Daniel said.
"It does," Matthew replied.
"That is not an explanation."
"It is storage."
"That is also not an explanation."
Hermione did not look up from her notes. "Dad, if you ask Matthew to explain expandable storage before breakfast, we will lose the morning."
Daniel closed his mouth.
Vivian brought tea.
Morrigan sat on the trunk lid and prevented it from closing.
That was probably intentional.
Hermione was kneeling beside the second set of Hogwarts books, writing labels in neat script.
Shared Study Copy — Hermione Granger
Matthew leaned over her shoulder. "That is not what we agreed."
She did not stop writing. "We agreed they were shared study resources."
"Yes."
"These are the copies I will use."
"You put only your name."
"I will add yours to the inside cover."
"That is backwards."
"It is organisationally clearer."
"It is possessive."
She turned her head slowly.
Matthew recognised the danger but continued anyway because accuracy mattered.
Hermione stared at him for three seconds.
Then she crossed out the label and wrote:
Shared Study Copy — Hermione Granger / Matthew Knight
Matthew nodded. "Better."
Hermione put the label down. "You are insufferable."
"You corrected the structure."
"Because you were technically right, which is worse."
That was when she looked at the owl perch Samuel had suggested they prepare.
Then the window.
Then the weather.
Then the distance between Dartford and Hogwarts.
Her expression sharpened.
"Owls are inefficient."
Matthew paused.
Vivian, who had been pouring tea, stopped moving.
Daniel looked up.
Helen sighed in the way mothers did when they recognised the beginning of an idea too late to prevent it.
Matthew turned fully toward Hermione. "Explain."
Hermione sat back on her heels. "Letters take time. Owls can be delayed by weather, distance, injury, interception, poor direction, or bad judgement."
Morrigan made a sound.
Hermione looked at her. "Yes, and apparently half-kneazle interference."
Morrigan blinked.
Hermione continued, "If you are at Hogwarts and I am here, owls are too slow for serious study corrections."
Matthew nodded.
Daniel looked between them. "Study corrections?"
"And emergencies," Hermione said.
Vivian's face tightened.
Matthew heard the second meaning too.
Not only questions about Charms.
Not only theory.
Dreams. Scars. Hogwarts. Dumbledore. Anything that reached Matthew while Hermione was not there.
He did not like how much the thought unsettled him.
Samuel's portrait had been brought upstairs in its smaller frame that morning, propped carefully on the sideboard because Vivian had said if he wanted to comment on breakfast he could do so from the room where breakfast happened.
Now the portrait leaned forward slightly.
"You are thinking of a linked correspondence object."
Hermione's eyes lit.
Matthew's did too.
Daniel immediately looked worried.
"I recognise that expression," he said. "Both of them have it."
Helen took his cup. "Drink before they explain."
"A linked book," Matthew said.
Hermione nodded. "Two books. One here, one with you. What is written in one appears in the other."
Daniel slowly put his cup down. "That sounds like a telephone with ink."
Hermione blinked. "A what?"
"A telephone. You speak in one place, someone hears in another."
Matthew looked interested. "Muggle linked voice device?"
Daniel stared. "Have you never used a telephone?"
"I dislike them."
"You dislike everything that rings."
"That is because ringing is rude."
Vivian smiled faintly. "Focus, please."
Hermione took out a fresh sheet of parchment. "The book must not activate as spellcasting every time it is used. The enchantment should already exist in the object."
"Otherwise Trace concerns," Matthew said.
"Exactly."
Samuel nodded. "The Ministry would not easily read a passive correspondence enchantment if properly bound, and within Hogwarts your copy would be surrounded by school magic. The home copy must be bound carefully through the sanctuary."
Matthew looked toward the hallway wall.
"Can the sanctuary anchor it?"
"Yes," Samuel said. "If we make it modest. Do not attempt a network."
Hermione immediately looked at Matthew.
Matthew looked offended. "I did not say network."
"You thought network."
"I thought future expansion."
"That is a network wearing a hat."
Gareth's travelling portrait, propped on the armchair near the trunk, laughed loudly. "She has him there."
Matthew ignored him.
Eleanor's frame sat beside Samuel's, and she looked at Hermione with approval. "The first version should be simple. Two books. Known users. No copied spell diagrams without safety marks. No sensitive names unless necessary."
Hermione wrote:
Rule One: not a toy.
Matthew watched her write.
Then he added:
Rule Two: not a secret from Nanny if safety is involved.
Vivian's eyes softened.
Hermione read the line.
Then nodded. "Good."
It took them four days to build the first pair.
Not because the enchantment was huge.
Because everyone kept stopping them.
Samuel stopped them whenever the rune structure became too ambitious.
Eleanor stopped them whenever the privacy rules were too weak.
Vivian stopped them whenever Matthew forgot to eat.
Helen stopped Hermione twice for trying to read while walking down stairs.
Daniel stopped everyone once to ask whether "a magical book that copies writing across distance" could also be used to send grocery lists, because that seemed more immediately useful than half the things they were discussing.
Gareth suggested adding an insult feature.
Hermione rejected it.
Morrigan sat on the second prototype until Matthew agreed to move the linked mark three inches lower on the inside cover.
No one knew why.
Samuel said to trust her.
Matthew objected.
Morrigan stared.
Matthew moved the mark.
The first prototype copied every third word.
The second copied everything backward.
The third copied perfectly, then refused to stop copying, including Hermione's irritated mutter of "ridiculous parchment."
The fourth worked for six minutes.
The fifth worked overnight.
The final books were plain, at Hermione's insistence.
Matthew's copy was dark grey with a small key-and-shield mark in the lower corner. Hermione's was dark brown with a smaller matching mark. They were not grimoires. That distinction mattered. A grimoire grew with the owner, held spells, organised knowledge, and could become a magical companion in its own right.
This was not that.
Not yet.
It was a bridge.
The first page held rules.
Hermione wrote the first.
This book is for communication, study, safety, and records. It is not a toy.
Matthew wrote the second.
If danger comes first, write danger first. Explain after.
Hermione wrote:
No experimental spellwork by book.
Matthew wrote:
No hiding injuries to avoid lectures.
Hermione stared at him.
He looked back.
She took the quill and added:
This applies to Matthew especially.
He wrote beneath it:
Hermione too, if she tries to study while injured.
Daniel, reading over their shoulders, said, "This is less a notebook and more a legal treaty."
Samuel said, "Good treaties keep people alive."
The first message was simple.
Hermione sat at one end of the sanctuary table.
Matthew sat at the other.
She wrote in her book:
This is a test.
The words appeared on Matthew's page in her handwriting.
Matthew wrote:
Received.
Hermione looked up.
Her face changed.
It was not excitement only.
It was relief.
"You will write when you reach Hogwarts."
"Yes."
"When you get on the train."
"Yes."
"When you arrive."
"Yes."
"When something hurts."
Matthew hesitated.
Hermione's eyes narrowed.
He wrote in the book:
When something hurts.
She looked satisfied.
Then she wrote:
Good.
The word appeared on his page.
Matthew stared at it longer than necessary.
Gareth looked between them and whispered loudly, "Oh, this is going to be unbearable."
Eleanor said, "Let them have the moment."
Hermione went red.
Matthew looked at the page and refused to look up.
The remaining weeks before Hogwarts were not quiet.
They studied as if September were a dragon and preparation was the only acceptable shield.
They had already been studying for more than a year and a half, ever since Matthew's tenth birthday opened the sanctuary and his magic began breathing properly again. The Diagon Alley supplies did not begin their education. They widened it.
By then, Matthew and Hermione were no longer beginners in the way most children were beginners.
They were still children.
Samuel said that often.
Usually while looking at Matthew.
But they had worked under portraits who did not waste time flattering them.
Samuel taught history, politics, magical law, the structure of power, and why every magical system had to be questioned at the point where protection became control.
Gareth taught Defence, duelling theory, battlefield movement, and how to recognise the moment courage turned into stupidity. He also taught three things he later admitted he had learned by surviving his own bad decisions.
Eleanor taught healing theory, curse wounds, protective spell structure, and why magic done to someone could be more dangerous than magic done near them.
The Grimoire taught slowly.
The Grimoire did not care that Matthew wanted more.
The Grimoire cared about readiness.
That made Matthew argue with it.
The Grimoire turned to a page titled:
Patience as Foundational Magic.
Hermione laughed for nearly a minute.
Matthew did not.
He copied the page anyway.
Gareth's wand trained Matthew's hand before his own wand came.
It liked movement, directness, and courage with a sharp edge. Matthew learned basic light charms, simple unlocking and locking charms, cushion charms, minor cleaning charms, warming lines, and the first forms of shield theory inside the sanctuary. He was not allowed to throw force spells at furniture after the chair incident.
Hermione did not let him forget the chair incident.
"It moved first," Matthew said.
"It was a chair."
"It was enchanted."
"It was still furniture."
Eleanor's wand trained Hermione.
That wand liked precision, structure, and questions asked in the correct order. Hermione's theory advanced faster than her practical casting at first because she tried to make every spell obey written logic before her hand had learned the movement. Eleanor corrected her gently. Gareth corrected her loudly once and was banned by Hermione from "helpful commentary" for two days.
By the time Matthew's own wand arrived from Ollivanders, his subjects were no longer at ordinary first-year level.
His Charms theory sat somewhere between second and third year, with practical casting held back only by caution and Trace restrictions outside the sanctuary.
His Defence theory was third-year in places, though Gareth insisted his formal duelling instincts still needed pressure.
His Transfiguration theory reached second-year foundations, and Eleanor warned him not to mistake understanding for safe performance.
His Potions knowledge was strong in ingredients, properties, timing, and substitutions, but weak in actual cauldron work because no one trusted him near heat and volatile liquids yet.
Hermione was similar.
Sometimes better.
She remembered more cleanly. She organised faster. She had a sharper instinct for why a rule existed. Matthew saw patterns first, but Hermione made them usable.
That was both excellent and irritating.
Runes became Matthew's problem.
Not a bad problem.
A problem in the way curry was a problem.
Important. Recurrent. Difficult to set aside.
He filled one notebook with rune terminology.
Then a second.
Then half of a third before Hermione took the book and wrote on the cover:
Rune Notes — Volume Three — Matthew Is Not Allowed to Carve Anything
He objected to the title.
Samuel approved it.
The Grimoire approved it by refusing to open to the next rune page until he copied the title exactly.
Matthew felt betrayed by literature.
Hermione enjoyed that.
Meanwhile, Cedric Diggory owled.
The letter was polite, direct, and very Hufflepuff.
His father had agreed to a commission if Madam Malkin supervised, if the enchantments were inspected, and if Matthew did not attempt anything that could be called armour by a Ministry official with poor imagination.
Hermione said this was sensible.
Matthew said Ministry officials had poor imagination by default.
Daniel said both statements could be true.
The final design took two weeks.
Cedric came to Madam Malkin's twice for fittings, both times with his father, Amos Diggory, who looked at Matthew with the wary pride of a man trying to decide whether commissioning magical clothing from a nearly twelve-year-old was madness or thrift.
Madam Malkin settled the question by behaving as if the arrangement were unusual but professionally legitimate.
That helped.
Cedric's ward-cloth was not a copy of Matthew's.
Matthew refused to copy.
"Clothes should fit the person, not the idea of the person," he said.
Hermione wrote that down because, annoyingly, it was good.
Cedric's outfit became something cleaner than Matthew's, less shadowed, less sharp at the edges, but still unmistakably practical. It blended elven armour lines with an assassin-style tunic structure and wizarding robes enough that it would not look out of place at Hogwarts. Deep charcoal formed the outer layer. Hufflepuff gold ran through the inner seams, visible only when he moved. The shoulders allowed full reach. The lower robe split cleanly for running, climbing, or broom mounting. The inner tunic sat close enough not to catch, soft enough not to restrict, and strong enough to take a minor impact.
The gloves were Matthew's favourite part.
Hermione said this was because he had become obsessed with hands.
Matthew said hands were important.
The gloves had incredible grip without feeling sticky. They used a mix of mokeskin, fine dragonhide reinforcement at the palm, and a thin tactile charm that preserved textile sensation. Cedric could feel parchment, wand wood, broom handle grain, rope fibre, and stone texture through them. The fingertips were sensitive enough for writing, climbing, and wand use, but the palms held firm even when wet.
The boots were the second-best part.
They gripped stone, mud, grass, and broom stirrups without becoming heavy. They had a minor ankle-stabilising charm, anti-slip tread, and a quiet-step line that was not strong enough for stealth work but enough to stop school corridors from announcing every footfall.
Madam Malkin approved the boots.
Hermione approved the gloves.
Matthew approved the whole thing.
Cedric tried it on in the back fitting room.
He turned once.
Then again.
Then bent, rolled his shoulders, raised one arm, crouched, straightened, and moved through three quick steps.
The cloth moved with him.
Not around him.
With him.
Cedric looked into the mirror.
For once, he had nothing polite to say.
That meant more than praise.
Amos Diggory stared too.
Madam Malkin looked deeply satisfied.
Hermione stood beside the fitting table with her checklist.
"Grip test."
Cedric took the rope she handed him, pulled, then climbed two knots higher on the testing frame than Madam Malkin had probably expected him to.
He dropped down, landing cleanly.
"Gloves hold."
"Textile sensation?"
Cedric picked up a quill, then a scrap of parchment, then his wand. He closed his eyes briefly.
"I can feel all of it."
Matthew nodded once.
That was the highest compliment to the charm.
Amos cleared his throat. "Price?"
Matthew looked at Madam Malkin.
Madam Malkin looked at him.
Hermione looked at both of them as though pricing was a moral exam.
Matthew had quoted one hundred galleons in the shop.
The final work had taken more.
Better materials. More testing. More tailoring. More supervised enchantment. Boots. Gloves. Growth allowance. Legal review. Madam Malkin's professional labour.
Matthew opened his mouth.
Hermione lifted one eyebrow.
He sighed.
"One hundred galleons," he said.
Madam Malkin's eyes flicked toward him.
Amos stared. "For all of it?"
"That was the quote."
Madam Malkin said, "It should be more."
Matthew nodded. "Next time it will be. This one is one hundred because that is what I said."
Hermione's expression softened.
Cedric looked down at the gloves, then at Matthew.
"That is fair."
Amos Diggory paid.
He counted the galleons with great care.
Madam Malkin took her professional share.
Materials were paid.
The remainder went into an envelope labelled:
Ward-Cloth Development Fund
Hermione wrote the label.
Matthew wanted to call it something better.
She refused.
Cedric wore the outfit out of the shop under his ordinary cloak.
He looked taller.
Not because the clothes changed him.
Because they made room for what was already there.
"Thank you," he said.
Matthew nodded. "Use it properly."
Cedric smiled. "That sounds like a warning."
"It is."
Amos looked at his son. "You commissioned clothing and got a lecture."
Cedric looked pleased. "Worth it."
The last night before Hogwarts came too quickly.
Matthew packed his trunk.
Then unpacked it.
Then Hermione repacked it because his system was "emotionally logical and physically absurd."
He had his school robes.
His ward-cloth.
His wand.
His linked book.
Gareth's borrowed wand returned to the rack.
The Knight ring remained in the sanctuary because Samuel said it did not belong at school unless needed.
Matthew had argued once.
Samuel had said no.
Matthew had accepted it.
Mostly.
Hermione stood beside the trunk with the linked book in her hands.
Her copy.
She had written her name inside the cover.
Not on the front.
The front remained plain.
"This is yours," Matthew said.
"I know."
"You can write whenever."
"I know."
"If something happens—"
"I write danger first."
"If you dream—"
"That is your category, not mine."
"If you find something—"
"I record first, decide later."
Matthew nodded.
Hermione looked at him for a long moment.
"You are going first."
"Yes."
"I hate that."
"I know."
"You will not get better by pretending Hogwarts does not hurt."
"I know."
"You will write."
"Yes."
"Properly."
"Yes."
"Not only when things become terrible."
Matthew paused.
She narrowed her eyes.
He sighed. "Not only when things become terrible."
"Good."
Vivian came upstairs and kissed his forehead.
Then held him longer than usual.
Matthew let her.
Daniel and Helen arrived the next morning to go with them to King's Cross. Hermione carried her linked book in her satchel like it was fragile and dangerous. Morrigan refused to come, which everyone agreed was probably for the best. She sat on the hallway table and watched Matthew leave with the grave displeasure of a queen whose knight had gone off to war under insufficient supervision.
Matthew looked back at her.
"I will write."
Morrigan blinked.
Hermione whispered, "You are now promising the cat correspondence."
"She is half-kneazle."
"That does not improve it."
At King's Cross, the barrier between platforms nine and ten waited.
Matthew had imagined this moment too many times.
In some versions, he felt ready.
In reality, he felt like he had a trunk, a wand, too many books, scars that still hurt, a linked book in his satchel, and a whole world ahead that had already lied to him once.
That would have to do.
Vivian fussed with his collar.
"Write."
"Yes, Nanny."
"Eat."
"Yes."
"Do not fight every fight."
Matthew looked at her.
She looked back.
He sighed. "I will choose."
"That is better."
Hermione stood beside him, face tight with too much feeling.
She did not cry.
Neither did he.
Instead, she pressed her linked book against his chest for one second, then pulled it back.
"Train first," she said.
"Train first," he agreed.
Daniel cleared his throat. "No chimneys today?"
"No," Matthew said.
"Excellent. I approve of trains."
Helen hugged him carefully.
"Be safe."
Matthew looked toward the barrier.
"I will be careful."
Hermione made a small sound.
He looked at her.
"I will try to be careful."
"Better."
The Hogwarts Express waited beyond the barrier, red and steaming, full of voices, owls, trunks, strangers, ghosts of future friends, possible enemies, and doors he had not yet learned how to open.
Matthew held the handle of his briefcase-sized trunk.
His wand rested warm inside his sleeve.
His linked book sat in his satchel.
Hermione's matching copy was pressed against her chest.
Matthew looked at her one last time.
"Not alone," he said.
Her eyes brightened.
"No," she said. "Not alone."
Then Matthew Knight stepped through the barrier and onto Platform Nine and Three-Quarters.
The first door to Hogwarts opened.
And this time, he carried his own key.