Three days after Kevin's meeting with Dumbledore, the headmaster came to find him.
"It's ready. Come."
He led Kevin up to the eighth floor — a stretch of the castle Kevin had been to maybe twice, high enough to catch good light from all directions, away from the dungeon draft and the damp that crept into Snape's laboratory on cold days.
The room itself was small: three metres by three, empty, one window facing east.
Dumbledore raised his hand. The room stretched — not dramatically, but decisively — expanding outward until it was fifteen metres wide and five deep, the window proportionally enlarged, a proper workspace visible in the new proportions.
"Fix it up however suits you," Dumbledore said, looking satisfied. "Workspace. Rest area if needed."
"Thank you, Professor."
This was his. A space at Hogwarts that was genuinely his, not borrowed, not shared with five other boys.
"One thing." Dumbledore's eyes crinkled. "This is a workspace. Not a private suite. Don't be arranging sleepovers for anyone who isn't supposed to be here."
Kevin coughed. "I have absolutely no idea what—"
"Mm." Dumbledore nodded. "I know you don't. Good. Stop by Snape this afternoon — he's been briefed on the course handover."
He left with the air of a man who had said precisely what needed saying.
Kevin unpacked his bag into the room methodically: shelves, cabinets, the worktable, ingredient stores, glassware. The left half of the room became the lab — good venting from the east window, workspace arranged for efficiency. The right half: a wide sofa, a low table. He didn't need a bed; a sofa with a decent cushioning charm was entirely adequate for the two or three hours he'd likely sleep here during long brews.
He stepped back and looked at it. Good.
Knock at the door, twenty minutes later.
He opened it. Hermione, in her reading cardigan, carrying a book.
"Professor Dumbledore told me." She looked past him into the room and her face did the thing it did when she encountered a well-organised space. Approval, followed by the urge to make it slightly better. "Extension Charm on the room?"
"Dumbledore did it."
She walked in. Examined the lab side, the rest side, the light.
"Can I come here in the afternoons? It's quiet, and the light's better than the library."
"Of course." He paused. "But—"
"I know. Not overnight." She sat on the sofa and folded her legs under her. "Dumbledore said something similar when I ran into him in the corridor."
Kevin sat beside her. He put his head in her lap without preamble.
She started running her fingers through his hair, which was what she did when she was being kind without making it formal.
"Tell me about Snape," she said.
He told her.
Snape had looked at him, said first through third years, handed over a stack of grades and syllabi covering approximately a hundred and forty students, said if more than ten fail their finals, I can remove you from the role immediately, and returned to his brewing.
Hermione was quiet for a moment.
Then: "I told you not to antagonise him."
"I was sharing good news."
"He turned it into a curriculum handover and a dismissal clause."
"I noticed."
She stroked his hair. "You know you can handle it."
"I know."
"So stop sulking."
"I'm not sulking."
She kissed his forehead. He burrowed against her side.
"Worst case, you quit," she said. "You wanted the room and the flexibility. If he makes the teaching untenable, you walk."
"Yeah." He said it into the fabric of her cardigan. "Though I'm not doing that."
She smiled and kept stroking his hair.
Word spread through the younger years within forty-eight hours: Snape was gone from first through third-year Potions, replaced by a teaching assistant whose name Dumbledore was keeping temporarily quiet.
The first class was a second-year combined Gryffindor-Slytherin session. Kevin walked in, said good afternoon, I'm Kevin, I'll be teaching you until the end of your third year, and let the noise happen.
It was significant noise. He was a Triwizard champion. He'd beaten a dragon. He was also, technically, their peer, which created a specific kind of energy.
Kevin let it run for thirty seconds, then raised a hand.
"Any questions about why a student is teaching you? Save them for Dumbledore. I didn't invent this arrangement, I just agreed to it."
He placed a written test on every desk. Six pages. Sixty minutes.
The noise that followed was a different kind.
"This covers your first half-year work and today's material," Kevin said. "The second part you'll have seen if you've read ahead, which I recommend. Previewing is not optional going forward."
He walked the room while they wrote, which was cruel in a very specific way — people tend to forget things they know perfectly well when someone capable of noticing is standing behind them.
When the hour was up, the papers flew back to his desk.
He gave the house points deductions for the students who had interrupted the room or made remarks during the test — five from Gryffindor, ten each from three Slytherins — calmly, without drama, while the class stared at him.
They'd expected a lenient senior student. He was not that.
The practical followed: Swelling Solution, first-half review. Standard enough, and most of them had brewed it before. A few went wrong — not dramatically, nothing needed to be extinguished — and Kevin moved through the rows, watching, correcting holds and timings, making notes.
Class dismissed. The students filed out talking.
He settled into the workshop that evening with a stack of graded papers and the correction notes from the practicals. Half the written tests had passed, barely. The solutions were more variable.
He stretched out on the sofa when he was done, genuinely tired.
This wasn't what he'd planned. He'd imagined a light advisory role — occasional guidance, the room, the flexibility, more time for his own work and Harry's preparation and Hermione.
What he'd actually agreed to was a real teaching load, graded responsibility, and a dismissal clause that Snape had clearly designed as a punishment and a test simultaneously.
His own fault, partially. He'd been honest with Snape at the worst possible moment and then underestimated the man's capacity for professional revenge.
He heard a knock.
"It's open."
Hermione came in with a plate of dinner from the Hall. She looked at his face when she set it down and said, with immense gentleness, "You look terrible."
"Thank you."
She sat beside him. "Everyone's talking about it. New teacher docked twenty-five points first day, gave a surprise test, anyone who failed has after-school sessions."
"It works," Kevin said tiredly. "Hit them with accountability immediately, they take it seriously. It's easier in every class after."
She patted his head. "You are a genius."
He pointed at his lips.
She kissed him without argument. He started eating.
"Second task is soon," she said, while he worked through the plate. "Don't let this run you down before it."
"I won't. First few weeks are the worst — new routines always are. Once it's set, it's manageable."
She was looking at the desk: the graded papers, the correction notes, the stack of syllabi Snape had dumped on him. She knew better than to say you didn't have to take this on. He had his reasons, and they were good ones.
She leaned against him instead and opened her lake creature book.
The routine settled in two weeks. Kevin taught one or two classes daily on weekday mornings, none on weekends. He split the years by house combination — Slytherin with Gryffindor, Hufflepuff with Ravenclaw — which gave him manageable numbers and some built-in inter-house friction to keep sessions interesting.
The students had hated him for a week and a half. Then the after-school sessions started and something shifted. Kevin didn't lecture at them; he sat at the worktable, asked what they'd gotten wrong, demonstrated the correction, let them try again. It wasn't Snape's approach — cold and adversarial and brilliantly effective for the talented — and it wasn't a soft option either. It was just direct.
By the third week, students from other year groups were turning up to the after-school sessions uninvited, standing at the back, watching.
Kevin had more than one student stay voluntarily after they'd already passed their retest.
He also had significantly less free time than he'd had before and was somewhat short on sleep, which was his own doing and which he was managing.
Harry and the rest had settled into the workshop as an afternoon base — more comfortable than the library, quieter than the common room, good light. Hermione had her Black Lake research laid out on the low table. Ron and Draco were working through spell theory. Harry was drilling Bubble-Head Charm forms.
"Second task's a few days out," Harry said, not looking up from his notes. "You're still teaching right up until?"
"Not the morning of. Dumbledore gave me two days free before. I don't need both, so I'll teach the day before."
Harry looked up briefly. Draco and Ron didn't bother looking surprised anymore.
Draco had been working up to something for the last hour — Kevin could tell by the frequency with which he almost said something and didn't.
"Kevin." He said it when there was a lull.
Kevin looked at him.
"Astoria Greengrass." He paused. "I've been talking to her more. She's — I mentioned you in class and she asked about you. I thought..." He stopped.
Harry and Ron had both gone very still in the manner of people pretending not to listen.
"You like her," Kevin said.
Draco's jaw tightened. "I don't know. Maybe. I want to know more, but I'm not sure how to—"
"Ask," Kevin said. "She'll either want to talk more, or she won't. Either way, you know where you stand, which is better than where you are now."
"But what if—"
"Draco. You like her. She's curious about you. Talking is a very achievable outcome." He paused. "Go ask her if she wants to study with you sometime. That's the whole plan."
Draco looked like he was considering this with the weight it deserved.
Harry, behind him, was pressing his lips together very hard. Ron had found something extremely interesting to look at on the ceiling.
"Fine," Draco said. "Fine, I'll — yes. Alright."
Kevin nodded. That was settled.
Hermione, from the corner where she'd been watching this with her book closed on her lap, thought that she had never in her life heard a romantic plan delivered with less fanfare. She supposed it was probably the right approach. It was very Kevin.