"Put it on," Draco said, placing the shimmering fabric in her hands.
Hermione ran her fingers along it. "It always feels like this — smooth, almost liquid. What is it actually made of?"
"Demiguise hair," Draco said. "They're gentle herbivores — look something like an ape, with very large eyes. The hair grows long and silver and has a natural invisibility property." He pulled a book from the shelf and opened it to the relevant illustration. "They're extremely rare. Which is most of the reason Invisibility Cloaks cost what they do."
Hermione studied the illustration for a moment. The creature in it had patient, dark eyes half-hidden by its fur. "They look rather wise," she said. "I imagine they'd rather not be found at all."
"Probably," Draco said. He glanced at the clock. "We should go."
"I know." She sighed. "It's just — I feel rather hypocritical. I've been thinking all year about the ethics of magical creatures and here I am wearing one."
"Prioritise," he said.
She pulled the cloak on and immediately ran into the problem of the collar. The clasp was fiddly, and every time she got it right her hair would escape from the hem. She was still wrestling with it when he said, "May I?" and stepped forward without waiting for an answer.
She looked at the ceiling while he adjusted the collar knot, aware of how close he was.
He paused. She wondered what he was looking at.
"I'm sorry," he said quietly. "Yesterday — when I grabbed your collar. Did I hurt you?"
"No," she said. "And I was trespassing in disguise. It wasn't unreasonable." She looked down at him. "You did startle me, though. I've never seen you like that before."
"I'm not usually." He finished the knot and stepped back. "But I'm always ready to be."
She didn't entirely know what to do with that, so she said nothing.
"Right," he said. "Let's go."
---
The common room had woken up while she'd been in his room. She could hear it before he opened the door — a dozen voices, the crackle of the fire, someone laughing at the far end.
Draco walked in without any change in expression, nodded to Pansy Parkinson, who was reading a copy of Wizarding Weekly in the corner, exchanged a few words with Marcus Flint's Chaser, and patted the shoulder of a Beater who looked like he'd had a difficult night. A perfectly ordinary Christmas morning greeting.
Hermione, invisible, followed at his heel and said nothing, watching the backs of their heads and thanking every lucky star she had that the Polyjuice Potion had worn off inside his room and not out here.
She had not thought the plan through sufficiently. She could see that now, with crystalline clarity. If Draco hadn't found her, she would eventually have had to leave the common room — through a door whose mechanism she had no idea how to operate, having followed Marcus Flint in through sheer opportunism — with the Potion wearing off around her and Pansy Parkinson seven feet away.
It would have been catastrophic.
Draco opened the outer door without looking back, held it just long enough for her to slip through, and they were out.
In the corridor beyond, she pulled the cloak off and handed it back to him. He folded it into a small, dense square and tucked it inside his robe.
"Thank you," she said.
"You're welcome." He glanced at her. "Don't do that again."
"I won't," she said, meaning it.
He fell into step beside her, unhurried — heading generally in the direction of Gryffindor Tower, though at a pace that suggested no particular urgency. She was acutely aware that he was walking her back.
"Tell Harry what we worked out," he said. "About the pipes. He's been subdued since Justin Finch-Fletchley was attacked."
"I will." She paused. "Are you going to be all right? You were up all night."
"I've been awake longer," he said. "Go on."
At the Gryffindor portrait hole, he stopped. She turned.
"If Professor McGonagall hears you spent the night somewhere that wasn't Gryffindor Tower," he said, with a composed expression, "I would appreciate not being described as a kidnapper."
"Obviously," she said.
She went in. The portrait swung shut behind her.
---
The Weasley twins found Draco at the foot of Gryffindor Tower approximately ninety seconds later.
They were wearing identical sweaters and identical expressions of great interest.
"We just saw Hermione Granger saying a very sincere goodbye to you," Fred said.
"At eight in the morning," George added. "On Christmas Day."
"We're friends," Draco said. "She had a question."
"Mm," said Fred.
"We'll leave it there," said George. "Anyway. We have a Christmas present for you. Come with us."
They pulled him toward the fourth floor before he could decline, and into an empty classroom near a statue of a hunchbacked witch.
Fred checked the corridor, closed the door, and placed something on the desk with the gravity of a man presenting a deed of property.
It was a large piece of parchment. Old, worn at the folds, slightly tattered. Apparently blank.
Draco looked at it.
"Go ahead," George said. "Think of it as a demonstration."
Fred touched his wand to the parchment. "I solemnly swear that I am up to no good."
Ink lines spread from the point of contact — thin and rapid, branching, filling the parchment with a detailed diagram. Corridors, rooms, staircases, towers, grounds. Every inch of Hogwarts Castle, rendered precisely, with names moving along its passages in real time.
"That's—" Draco stared. "Is this the whole castle?"
"Every room," George said, with audible satisfaction. "Every passage. Every person."
"Where did you get this?"
"Filch's filing cabinet, first year," Fred said. "He'd confiscated it from someone, years back. Filed under 'Highly Dangerous.'"
Draco leaned closer. The names moved as he watched — dotted lines of footsteps trailing each one. He scanned the grounds, the towers, the corridors below.
"There are seven passages to Hogsmeade," George said, pointing. "Filch knows four. The other three are ours. The one on the fifth floor has collapsed — we checked last week. The one under the Whomping Willow on the grounds is also currently unusable. But this one—" he tapped a passage running north from the castle "—leads directly to the cellar of Honeydukes. Entrance is right outside this classroom. The statue."
"The one-eyed witch," Draco said.
"Tap the hump and say 'Dissendium,'" Fred confirmed.
Draco straightened. He looked at them. "You're giving this to me."
"We've memorised it," George said. "Besides, you need it more than we do at this point. You want to visit Hogsmeade, and you want to keep track of things. This does both."
"When you're done using it, say 'Mischief managed,'" Fred said. "Otherwise it stays open, and if Snape finds it — well. Don't let Snape find it."
"The map was made by Moony, Wormtail, Padfoot, and Prongs," George added. "Whoever they were, they were brilliant."
Draco stared at the parchment for another long moment. Then he picked it up.
"Thank you," he said.
"Merry Christmas," said the twins, simultaneously, and left.
---
For the next several days, Draco was largely unavailable.
He appeared at meals and in the common room, but he had the distracted quality of someone whose attention is entirely elsewhere. Blaise, who had expected a chess partner, found himself redirected to Pansy, who beat him six times in seven games and then insisted he honour the consequences of a bet he maintained he had never agreed to.
Draco barely registered any of this.
He lay on his bed with the map propped against a pillow and tracked the slow, purposeful movements of Hogwarts.
Irma Pince and Madam Pomfrey occasionally appeared together at Madam Puddifoot's Tea Shop in Hogsmeade — he hadn't known they were friendly. Crabbe and Goyle spent most of every day in the vicinity of the Great Hall kitchens, which was not surprising. Percy Weasley and Penelope Clearwater of Ravenclaw frequently appeared in the same corner of the library with their names very close together.
Professor Snape's name appeared in the men's bathroom at regular intervals. This, Draco noted, definitively resolved a question he had been too professionally cautious to investigate.
He tracked Filch's name as it lingered in the third-floor corridor at the same time every morning — sitting in a chair, apparently, watching students pass. Looking for culprits.
The Chamber of Secrets didn't appear on the map. Its entrance, wherever it was, had either been hidden before the map was made or by means its makers hadn't known about. The Basilisk didn't appear either. Whatever the map tracked, it tracked human-named inhabitants — and the Basilisk had no name anyone knew.
Still, the map was extraordinary. It was the closest thing to actual omniscience he'd ever held.
He was studying it one morning — still in bed, the light through the dungeon windows dim and green — when his eye caught something that stopped him entirely.
He sat up.
There, at the Gryffindor table in the Great Hall, were the names Harry Potter and Ron Weasley.
And next to them, overlapping almost exactly with Ron's name: Peter Pettigrew.
Draco stared at it.
Peter Pettigrew. Wormtail. One of the Marauders — the one who had betrayed James and Lily Potter to Voldemort, faked his own death, and hidden for twelve years in an Animagus form no one had thought to look for.
Currently, according to every official record, deceased.
Draco was out of bed before he'd fully decided to move.
---
The Great Hall was quiet. It was early — most of the castle was still asleep — and the Gryffindor table had only two occupants: Harry and Ron, making their way steadily through breakfast.
Three names on the map. Two people visible.
Draco checked the parchment once more from the doorway, gripping his wand, then crossed the hall and sat down across from them.
"Good morning," Harry said, looking faintly puzzled by both the location and the expression. "Are you all right?"
"Fine." Draco looked between them. "Were you with anyone just now? Before I came in?"
Ron looked up from his eggs. "Just us. Why?"
Draco studied them. Harry's expression was open, curious, slightly concerned. Ron's was merely confused, with egg on his chin. Neither of them showed any sign of being coerced, aware of anything unusual, or in the presence of someone they knew to be in hiding.
He looked at Ron.
Ron had a rat.
He had a rat that he'd had for years. A rat that was old, and frequently lethargic, and which Ron kept in his pocket and occasionally brought to the table.
A rat that was sitting next to Ron Weasley on the Marauder's Map under the name Peter Pettigrew.
Draco made himself breathe normally.
The map had been made by Moony, Wormtail, Padfoot, and Prongs. Wormtail was Peter Pettigrew. Peter Pettigrew was an Animagus who transformed into a rat.
The map tracked all living creatures in the castle by name. Including Animagi. Including Peter Pettigrew, who was currently in Ron Weasley's pocket in the form of a rat called Scabbers.
"Draco?" Harry said.
He realised he had been staring at Ron in silence for an unsettling length of time.
"Sorry," he said. "I didn't sleep enough. Good morning."
He had no idea what to do with this information. Not now — not today, on a quiet Christmas morning when the hall was nearly empty and the worst he could prove was that Ron had a suspiciously long-lived rat. He needed to think.
The portrait hole swung open at the far end of the hall, and Hermione came in with cold-flushed cheeks and her arms full of parchment.
"There you are," she said, and then: "Draco, your collar's crooked."
She sat down beside him and straightened it with the matter-of-fact efficiency of someone tidying a bookshelf. He sat very still.
"Thank you," he managed.
"You two finally made up?" Harry said, smiling behind his pumpkin juice.
"I don't know what you mean," Hermione said, spreading parchment across the table. "Have some bread, Draco. You look like you haven't eaten."
She pushed a plate toward him. He took a piece of bread and tried to remember what he had been thinking about before the collar.
Peter Pettigrew. Scabbers. Right.
"We asked around," Harry said, lowering his voice. "Several Gryffindors were in Filch's office around that time — we've made a list."
"Slytherins too." Draco pulled his attention back to the table. "I've marked up the likely candidates."
"Here's mine, Harry's, and a partial Hufflepuff list from Susan Bones," Hermione said, sorting the parchments. "I'm going to cross-reference today."
"Ginny says Colin hasn't offended anyone," Ron added, from the other end of a fried egg. "She's his Charms partner."
"We should verify with a few more of his classmates," Hermione said. "Ginny's been frightened since the attacks started — she might have missed something."
"My sister is perfectly sharp," Ron said, with a frown. "She'd have mentioned it if there was anything to mention."
"I'm not doubting her. I'm saying independent cross-verification is good practice." Hermione didn't look up from her list. "I'll ask around myself."
Ron looked as though he was going to argue, then apparently decided against it. "Fine. Sorry. Things have been a bit stressful at home."
"I know," Hermione said, more gently. "I'll also check in with Ginny — sometimes it's easier talking to another girl about things that frightened her. And it might help her feel like the problem is being actively worked on."
Ron relaxed fractionally. "Yeah. All right."
Draco looked at her.
She was still scanning the list. It occurred to him, not for the first time, that she was considerably more strategically capable than she appeared when she was arguing with him.
"Ravenclaw is the gap," she said. "I have no reliable contacts there. Parvati's sister is in Ravenclaw, but she talks, and I don't want this getting around."
"I may have a way in," Draco said. "Give me a day or two."
He had been watching the Grey Lady's name appear periodically on the map near a name he recognised — Luna Lovegood. If they were on friendly terms, Luna might be willing to ask the questions Draco couldn't easily ask himself.
"Excellent," Hermione said, with a brightness that he found he didn't mind at all. "I genuinely appreciate your special channels, Draco."
"Don't call them special channels."
"Then tell me what to call them."
He didn't answer. Across the hall, Crabbe was beckoning at him from the Slytherin table with the expression of someone delivering an urgent summons.
"I have to go," Draco said, standing. "I'll have the Ravenclaw information as soon as I can."
"Thank you," Hermione said, already turning back to her list.
He walked back to the Slytherin table — where, apparently, Pansy had beaten Blaise at Wizard Chess and was now insisting on the terms of a bet whose existence Blaise disputed entirely — and pulled the Marauder's Map from his pocket under the table.
Peter Pettigrew's name was still exactly where it had been. Overlapping Ron's. Barely half an inch of parchment separating them.
Draco smoothed the map flat and looked at it for a long time.
Somewhere in this hall, in Ron Weasley's pocket, one of the most dangerous men in the wizarding world was eating stolen scraps and sleeping in a cage and waiting.
For what, Draco wasn't yet sure.
But he intended to find out.