The evening at the Grangers' ran long.
Hermione hadn't been home properly in months, and her parents knew it, and the three of them had a great deal of catching up to do over dinner — the kind that Kevin mostly listened to with half a smile, watching how her face changed when she was with them, easier and younger than she allowed herself at school. He took note of the rhythm of it. Filed it away.
He'd spent the actual dinner topping up protective charms throughout the house under the cover of normal movement — asking for the salt, heading to the bathroom, wandering into the kitchen to help clear plates. Tiny trigger-spells, each one invisible, each one linked to his awareness. If magic crossed the threshold of this house, he'd know it from Hogwarts and he'd be here.
It wasn't as elegant as what he eventually intended. Eventually he'd work out how to embed something directly onto the Grangers themselves — something keyed to their specific life signs, fine-tuned enough that he'd feel it if anything went wrong. But that required alchemy he didn't have yet.
He'd dumped the spare talent points into alchemy as soon as the System confirmed the reward — brought it up from seven to twelve. Then sat down with his books and discovered very quickly that twelve was genuinely insufficient.
Alchemy was not a subject. It was a discipline, and the distinction mattered. Every other class at Hogwarts taught you to perform specific techniques in sequence. Alchemy expected you to have already mastered those techniques and was interested only in what you could build by fusing them. Potions knowledge shaped how you worked with catalysts. Charms theory determined how you encoded intent into an object. Transfiguration gave you the structural grammar. And all of it had to hold together simultaneously.
Kevin was good at all of those subjects. He was not yet good enough at all of them at once.
He needed a teacher.
He noted it on the mental list — Dumbledore, next term — and went back to trying to extract a protective principle from Chapter Four that was almost making sense.
He was still at it at three in the morning when the knock came.
"Kevin." Hermione's voice, half-sleep, half-serious. "Your light."
He cracked the door. She stood there in her nightgown, hair down around her shoulders, squinting at him with the particular expression she wore when she'd decided something was going to stop.
"Alchemy," he said, before she could ask.
Her eyes sharpened. "Those are the books we bought together. We were supposed to study them together. I came home and you'd started without me—"
"I only covered the introductory sections."
"At three in the morning."
"Time got away—"
"Bed," she said.
He closed the book.
She watched him do it. Then she watched him put it back on the shelf. Watched him check that the shelf was straight. Watched him show every sign of a man who was going to open the book again the second she left.
She left.
He sat down.
A minute later, the door opened again.
Hermione stood in the doorway holding a pillow, her face the particular shade of determined that meant she had committed to a course of action and was going to see it through even if it embarrassed her.
"I'm sleeping here tonight," she announced. "To make sure you actually stop."
She didn't wait for an answer. She stepped past him, climbed into his bed with the decisive authority of someone annexing a strategic position, pulled the covers up, and said: "Light off. Sleep."
The command was somewhat muffled by the pillow, but its authority was not in doubt.
Kevin extinguished the light and got in beside her.
Then he pulled her in close from behind.
"Hey!" She went rigid. "What are you—"
"I need to hold something to fall asleep," he said. He said it with complete sincerity, which made it worse. "New habit. You took the good side of the bed, so you're elected."
"That is an obvious lie and you know it."
"It's a recent truth. Very recent. Started right about when you climbed into my bed."
She made a sound that was half outrage, half involuntarily fond, and didn't move away.
We're dating now, she told herself firmly. This is acceptable.
Her mother's very specific advice about other things that were not acceptable until everyone involved was a proper adult returned to her at volume. Her face heated up.
Kevin's hands, which had been settled at her waist in a perfectly reasonable manner, became gradually less reasonable.
"Kevin."
"Mm?"
"Hands."
"Sorry. Hermione's very—"
"Don't finish that sentence."
"—warm," he finished.
She couldn't tell if it was innocence or deliberate provocation, which was part of why he was impossible to deal with. She caught his hand and held it still.
He was quiet after that. Then quieter. Then the particular silence of someone who had fallen asleep mid-thought, his breathing evening out against her hair.
Hermione let out a slow breath. Her heart rate returned to something approaching normal.
She lay in the dark and listened to the house settle around them. The soft sounds of the neighborhood outside. The familiar smell of Kevin's room — the particular combination of clean wool and something faintly sweet she associated, without being able to explain it, with safety.
It was fine. It was all fine.
She was just going to have to have a very serious conversation with herself about what qualified as supervision.