I need, Hermione thought firmly as she walked back and forth before Barnaby the Barmy before breakfast the next morning, a room with lots of keys.

When the door appeared, it opened onto a room that was little more than a cupboard — but one lined with hooks, from which hung keys of every conceivable description. Huge ornate keys that looked like they'd unlock St Paul's Cathedral — car keys — tiny keys no larger than the nail on her little finger —

She rejected each in turn. It has to be something small enough to carry in a pocket something that fits with the wizarding world … something too big to get accidentally lost …

She reached for the perfect one: an old-fashioned door key, one that looked like it might easily open a classroom or storeroom door here in Hogwarts. It was worn and dull, but the bow was ornate and, when she studied it, beautiful in a slightly strange way, with intertwining cords wrapping around it. She weighed it in her hand and felt its solidity. Perfect.

"I'm going to have to ask," Ron said behind Hermione, and she jumped. He leaned forward to peer over her shoulder. "What by Merlin's saggy right —"

"Ron!"

"— sock," he went on smoothly. "Made you need a locksmith's storeroom."

"I needed a key," Hermione said. She put the one she'd chosen in her pocket and closed the door.

"Having trouble with your Alohomora?" Ron fell into step with her as she started back down the corridor.

"As if," Hermione retorted. "No, it's for —" She paused. "It sounds a bit mental when I say it out loud."

"As mental as my best friend having a bit of old Coldysnort stuck in his head for most of his life? No?"

"No, not that mental," Hermione agreed. "There are these three first year students. They're a bit … well, let's say they need something to focus their attention."

"Troublemakers," Ron translated.

"No, not exactly," Hermione said. "I mean, they don't muck up in class for no reason, and they do their homework, but I caught one of them pinching the ingredients for Hair Raising Potion the other day, and I'm almost sure the other two were in on it."

"So you're going to … hit them with a key?"

"I was thinking," Hermione said, hearing a preemptive defensive note in her voice, "that it might be good for them to have a bit of direction for their extra-curricular activities, so, you know, they could be steered towards learning useful things. Like we had."

"That is mental," Ron said cheerfully. "We weren't so much steered towards useful things as trying not to get killed while in over our heads."

"Well I don't intend to send them off to destroy the seven separate parts of a dark wizard's soul," Hermione snapped.

"Why don't you just give them detention?"

"Because that worked so well on you and Harry," Hermione said. "I remember many a time when the two of you stopped before running off the the Forbidden Forest, or the Restricted Section, and said 'oh, we'd better not go, I'd hate to get detention'."

Ron laughed. "Alright, fair enough. So what's your plan?"

"I'm going to make sure they hear about the Quidditch Key — a key that attracts the Snitch to whoever is carrying it."

"That's brilliant!" Ron said enthusiastically. "I wish we'd had that —"

"It doesn't exist, Ron," Hermione said. "It's just an ordinary key."

He deflated a bit. "Oh. Right. That makes more sense. So you tell them about the imaginary key — actually, it's better if they hear about it accidentally, right? Work it out themselves."

Hermione nodded. "And then I'll hide it somewhere, and — well, there will have to be tasks, or tests, won't there?"

"Like with the Stone!" Ron said. "A chess game — I bet Neville's got some Devil's Snare —"

"I don't know if any of them are any good at chess," Hermione said. "Or Herbology. It has to be something they can pass. With effort."

"Then that's your next step, isn't it?" Ron said as they rounded the corner and started down the stairs. "Find out what they're good at."

Hermione sighed. "It really is a completely mental idea, isn't it? As if I have time to do any of this, between teaching, and marking, and, you know, the other thing."

"I think you should do it," Ron said, surprising her. He punched her lightly on the arm. "You haven't looked this, I dunno, happy or something, since we got here."

Hermione bit her lip. "What if I mess it up somehow? If they get hurt?"

"We'll help," Ron said easily. "Harry and Ginny and me. And Neville and Luna, too. And you have to work it out first, right? We might have the curse broken before you're even ready — both curses, even." He grinned down at her. "And then we'll be dying for something interesting to do. You'll be doing us a favour, really."

"Oh, really?" Hermione said, trying and failing not to grin back.

"No, it's a complete lie," Ron said. He opened the door to the Great Hall with a swish of his wand, garnering impressed stares from the students waiting to enter. "But I'll help anyway."

As she spread marmalade on her toast, Hermione mulled over what Ron had said. Happy or something. She supposed that was true. After all, ever since I've arrived here I've been worried. About not telling Harry and Ron about Professor Snape; about Professor Snape himself, even before I knew what was really wrong with him. About teaching. About everything, really.

And it wasn't as if she was completely confident about the absolutely mental plan of making up a quest for three eleven-year-olds and making sure it was, as Severus Snape had said, a very small and very safe quest. But somehow, she felt better about what was unquestionably a completely unorthodox and probably inappropriate approach to her students than she had about any of her classes, even the successful ones. Talking about it with Professor Snape, she'd felt for the first time like a member of staff, an equal to him and not just the former student he was determined to mould into a competent teacher.

It was the only subject they'd managed to discuss without the conversation somehow being poisoned by his bitter sarcasm or his grudges. For a few moments, she'd been able to forget that he was Professor Snape, terror of the dungeons, and he'd just been —

A friend.

Hermione gave herself a mental shake. Harry was a friend. Ginny was a friend. Ron, thankfully, was once again a friend.

Severus Snape is a colleague at most. She couldn't imagine him ever having friends, let alone being one of his friends herself.

The swooping owls with the morning post broke into her train of thought. A copy of the latest issue of Transatlantic Potions dropped next to Hermione's plate and she picked it up, making a mental note to make sure not to leave it in her room. Professor Snape will be interested in it, too.

"Oh, good," Luna said happily. "Daddy found them!"

"Crumple-horned snorkacks?" Neville asked, but kindly.

"No, we won't get another chance to look for them before Christmas," Luna said. She showed them an open envelope, the edges of a photograph showing. "He found these. They're from 1984. I can't tell you what's in them until later, though."

"Clubhouse after dinner," Harry said. "I was going to suggest it, anyway."

Hermione didn't have time, during the day, to think any more about the Quidditch Key. She tried a little unobtrusive eavesdropping on the Terrible Trio during her first year class, to see if she could pick up any clues on the sort of things that interested them and might make good challenges for their quest, but they were focused on their brewing and barely said a word that wasn't related to the lesson.

She smiled at her own frustration. I ought to be delighted at their diligence — as their teacher, I should take it as a compliment.

Lunch was again, despite the promise Professor Snape had extracted from her, sandwiches at her office desk as she ploughed through still more marking. She had accepted — she had been forced to accept — that she couldn't give every single essay the kind of detailed reading and critique she was used to giving to Harry and Ron's homework. Still, she couldn't bring herself to dismiss any student's entire work at the first mistake, the way Professor Snape did.

She sighed, dipped her quill, and wrote Although you have accurately described the stages of brewing, I can't assign a grade to this essay as your confusion between wormwood and woodfern renders the rest nonsense. Redo, resubmit.

The afternoon allowed for no more time for thought than the morning had, and by the time Colin Aitkins appeared to serve his detention, Hermione was once again having second thoughts about her plan.

She had decided to take inspiration from something Professor Snape had once done to Harry for this evening's detention — minus the personal grudge and the cruelty, of course.

"Mr Aitkins," she said, pointing to a box set on one of the desks. "It's come to my attention that some of the classroom records have fallen out of order. This evening, you will organise them by date, with the most recent at the front, and the oldest at the back."

"Yes, Professor," he said, and quickly took a seat, lifting out a mass of records.

Hermione kept an eye on him as she pretended to be completely absorbed in her marking. She had to suppress a smile at his first gasp of horror: the records she had carefully disordered were the accident reports the Potions Professor was required to fill in whenever a student injured themselves or others with a brewing error, inside the classroom or out of it.

She'd carefully extracted the one bearing her own name dated 1993, and it was tucked beneath her pile of marking. Remembering the incident was bad enough. There's no way I'm going to read what Professor Snape must have said about it.

But there were far more dramatic and damaging incidents in the pile Colin was working his way through. Hilda Metherson, who in 1987 had chanced her arm at brewing a love potion and sent the object of her crush to St Mungo's for three months. I can only conclude that he had a lucky escape, Snape had written. Jonas Jefferson, who in 1976 had attempted Liquid Luck and levelled his dormitory in the resulting explosion. Sadly, we are still looking for Mr Jefferson's left leg, Slughorn had noted.

If reading through the accounts of what had happened to previous students who thought themselves ready to brew complicated potions on their own didn't sober Colin Aitkins, Hermione wasn't sure what would.

Behind Colin, the classroom door swung open, as pushed by a breeze. Except, as Professor Snape pointed out himself, there's no bloody breezes down here.

Hermione waited, and after a moment, out of Colin's sight, a jar on one of the shelves turned slightly and moved to be in more precise alignment with its neighbours. Fine. At least he's announced himself.

She got up and went to close the door. "How are you going with those, Mr Aitkins?"

"Almost done," he mumbled, looking a bit green. Hermione passed by him on her way back to her desk and glanced over his shoulder. Mathilda Forrest, 1983. That had been a nasty one: Snape's handwriting had been particularly dark and jagged as he wrote The frogs should cease to emerge from her orifices within three weeks, a wholly inadequate consequence for her arrogance and ignorance.

"Mr Aitkins," Hermione said. "I think you're clever enough to understand why I asked you to assist with my filing."

He gulped, and nodded. "To make me think twice."

Hermione hooked the nearest stool towards her with her foot and sat down. "You did promise me that you'd come and ask before doing anything mad, you know."

Colin blinked at her. "It had nothing to do with the Restricted Section!"

Hermione sighed, and pinched the bridge of her nose for a few seconds. "Mr Aitkins. Extrapolating from what I said about the Restricted Section to the subject of stealing potions ingredients for illicit brewing, what do you think you should have done?"

"It's not brewing," he said quickly. "Really, it isn't, and we have permission."

Hermione felt her eyebrows rise in what was almost a Snape-like manner. "To thieve from the storeroom?"

He looked away. "Well, no, not that."

"If you're not brewing —" Hermione stopped herself saying Hair Raising Potion, reflecting that it was probably better not to give him any ideas he hadn't already come up with. "Then what do you want the ingredients for?"

"An infusion. Madam Lovegood said —" Colin faltered to a halt.

From the apparently empty side of the classroom, Hermione distinctly heard Professor Snape snort.

"And why did you ask Madam Lovegood and not me?" Hermione asked. She waited, but Colin only looked at his hands in silence. "Was it, maybe, because you thought you'd be more likely to get the answer you wanted?"

"Partly," Colin admitted miserably. "But also because she was there, in the Library."

"And what were you looking up, in the Library?"

"Stuff," Colin said.

Stuff. It had been twelve years, and Hermione had forgotten how remarkably uncommunicative eleven-year-olds could be, when they chose to be. Part of her longed to raise an eyebrow and say Stuff, Mr Aitkins? How remarkably precise of you, exactly as Snape would have done.

Instead, she simply looked at him steadily. "You'll have to do better than that."

"Broom handle polish," he admitted in a whisper.

"Broom handle — why on earth not just order it like everybody else?"

"We found a recipe. Maisie said it would be better than anything we could order. And she could be a Beater, on the Hufflepuff team, you know, except her broom … it's not fast enough."

Well, that answers one question — they'll definitely be interested in the Quidditch Key.

Just as Snape had predicted.