Catalyst and Inhibitor

Isilarma

Written for Cheeky Slytherin Lass for the Gift-Giving Extravaganza 2014. I hope you enjoy it.

Disclaimer: I do not own Harry Potter and am not affiliated with Bloomsbury or Scholastic Inc.

In first year he notices her.

Academic achievements were valued in Percy's family. His mother exclaimed loudly over every letter detailing Bill's exemplary marks, and she constantly encourage her younger children to do their best. She was just as proud of Charlie's sporting achievements, but Percy knows that sports are far from his strong point. If he's going to excel it'll be in the classroom, not on the Quidditch pitch. He pores over his books for weeks before term starts, determined to do the very best he possibly can.

The hat seriously considers putting him in Ravenclaw as a result, but he ends up in Gryffindor with the rest of his family. A small part of him is disappointed, but he pushes it aside. You don't have to be in Ravenclaw to be clever, and he's going to prove it.

Unfortunately, the Ravenclaws seem equally determined to show their own brains.

"That is correct, Miss Clearwater. Ten points to Ravenclaw."

Percy stares. The girl, he remembers the name Penelope from the Sorting, stares back. She's tiny, with bright blue eyes and curly hair, and she gives a bright grin as she meets his gaze.

Percy grits his teeth. She might be Ravenclaw, but she is not smarter than him.

In second year he decides he hates her.

"Looks like I beat you again, Weasley."

Percy glares back. "Yeah, well I still did better in Potions. And Charms."

"But Transfiguration is the hardest," she points out. "So if I'm doing better than you in that, it must mean I'm smarter."

"That's stupid," Percy growls, but his stomach knots uncomfortably. Transfiguration is the hardest subject, McGonagall said so. But that means she is smarter...

Percy can't accept that. He isn't cool like Bill, he can't play Quidditch like Charlie, and he's definitely not funny like the twins. If he isn't smart, then what is he?

"Percy?"

"Go away," he hisses. "I hate you."

Penelope frowns at him. "Now you're the one being stupid. Why do you think you have to be smarter than everyone; it's not a competition."

He can't answer that. It's another reason to hate her.

In third year he avoids her.

With Fred and George starting at Hogwarts, Percy knows he'll have to be careful. He has a duty to look after his younger siblings; no matter how many times they say they don't want or need his help he's still their big brother. Bill and Charlie have more important things to do than babysit, so it's going to be down to him to keep them out of trouble.

Percy doesn't mind that. Annoying as they might be, he really does want to make sure his brothers are all right. It does mean that he's going to have to be more careful with his work though; he can't afford to fall behind.

"Hey Percy, do you want to study with us?"

Percy spares a glance up. "I don't have time."

Penelope folds her arms. "You'll learn it better in a group."

That might be true, and for a moment he's tempted. But learning in a group is slow, and he wants to make sure Fred and George get to their detention on time. "No, thanks."

Besides, he still doesn't like her.

"Fine. Learn it wrong then."

He really doesn't like her.

In fourth year he learns to tolerate her.

"Anyone sitting here?"

Percy has shaken his head before the identity of the speaker fully registers, and by then it's too late to protest as Penelope slips into the seat opposite him. He grits his teeth and concentrates on his book. There's no need to talk; they're both here to work, not socialise. Hopefully she'll realise that too.

Thankfully, Ravenclaws, unlike Gryffindors, understand the value of silence. Percy is able to work on his Transfiguration essay for another half an hour before an exasperated sigh meets his ears.

"Stupid potion."

Percy considers ignoring her, but he knows if he does that the interruptions will just continue. He sighs and looks up. "What is it?"

Penelope starts and looks up. "I'm sorry?"

"What are you doing?" Percy repeats. This was clearly a bad idea. Penelope studies him a moment then swivels the book so he can see.

"It's those antidotes Snape was talking about. I'm just struggling to get my head round them."

This is such a bad idea. "You're using that equation wrong," he mutters.

"Show me."

Percy hesitates. He understands it, but he really needs to get his essay done. Penelope glances at his parchment and gives a small smile. "I can show you where you're going wrong there."

"All right," says Percy slowly. It's a reasonable trade, and just talking about work should be fine.

After all, if there's one thing they have in common, it's a desire to excel.

In fifth year he starts to really see her.

He's a prefect. Just like Bill was. Percy knows that if he keeps going like this, he has a good chance of being Head Boy. The thought is enough to inspire him to work even harder. And maybe there's another incentive.

"I knew McGonagall would pick you."

He nods at the blue and bronze badge pinned to her robes. "And I thought Flitwick would pick you. Congratulations."

"Thanks." She sits next to him without asking, but doesn't give him a chance to protest. "So, got any brothers starting this year?"

"Last one, Ron." He pauses, but wants to see the look on her face. "And there's Harry Potter, of course."

Her eyes widen, then narrow. "Of course, he would have turned eleven." Her expression turns thoughtful. "I hope he'll be all right."

Percy frowns. "What do you mean?"

"Well, he's the Boy Who Lived, and he hasn't been brought up with us. It must be a bit overwhelming."

He hasn't considered that, but it makes sense. Starting Hogwarts was amazing, but it wasn't easy, and he had older brothers who had told him what to expect. Harry Potter wouldn't have that, and he'll also have his celebrity status to deal with. It's a lot for an eleven year old. "We should keep an eye on him. If he ends up in one of our houses that is," he clarifies quickly.

"And even if he doesn't," Penelope suggests. "He is all on his own after all. He'd probably be glad of someone to go to if he needs help."

Percy blinks, but in the face of her determination, he can only nod. "We can try, I suppose." Penelope smiles, but something in her eyes, prompts Percy to ask, "Do you have any brothers or sisters?"

Her smile turns wistful. "One sister. She's four years younger than me. She doesn't have magic."

Percy suppresses a wince. His siblings might be annoying, but he doesn't like being completely separated from them. The twinge of guilt is harder to avoid; five years and he never knew she had a sister. "What's she like?"

Her eyes narrow. "Why the sudden curiosity?"

Percy shrugs. "You know all about my family. It's hardly fair if I know nothing about yours."

Penelope studies him for long enough that he has to resist the urge to fidget, but the smile that lights her entire face is worth it. "Good point."

Percy allows himself to relax as he listens. She isn't that bad, really.

In sixth year he begins to think he loves her.

Percy first read Hogwarts: A History when he was nine. He was excited about the prospect of going to Hogwarts, and desperate to learn all he could. He absorbed everything his parents and older brothers could tell him, and went hunting for more. He read the entire thing cover to cover in less than a week.

So he isn't at all ashamed of the rush of fear he feels when he reads the words written in blood, words that threaten only certain students.

Penelope doesn't exactly share his concerns.

"It's just a legend, Percy. There's no evidence at all."

"We have a wall covered in blood," Percy shoots back. "That seems pretty conclusive." Penelope bites her lip, and any irritation he feels evaporates. "Look, even if the Chamber is a myth, you can't ignore the fact that it looks like someone has got it in for Muggle-borns."

Penelope lays a hands on his arm. "Percy, I'll be fine. It's not like the teachers are going to let anything happen."

Percy could remind her of how his little brother nearly died last year, but even he recognises that this isn't exactly the time. "Just promise me you'll be careful," he whispers.

Penelope smiles and kisses him. "Of course."

And then the attacks begin, and he continues to remember the legends. He tries to keep an eye on her, but he's also trying to fulfill his duties, and look after his siblings, and keep up with his schoolwork, and he can't be everywhere at once.

He sees her lying frozen in the hospital wing and feels like he's been petrified himself. Nothing could ever have prepared him for this. Given a chance he would trade places with her in a heartbeat, but as it is, there is simply nothing he could do.

Ginny's disappearance is the last straw. He doesn't care about setting a good example. Being a model student suddenly seems pointless. He's lost the two most important girls in his life, and nothing compares to that.

He somehow gets a second chance, thanks to his little brother and his friend. He swears that he will never take her for granted again.

And he wonders just when the annoying Ravenclaw became so important to him.

In seventh year it ends.

Some people marry their childhood sweethearts. Percy knows that his parents began dating while they were still in Hogwarts and married soon after, and their relationship is still the strongest he knows. He also knows just how rare that kind of relationships is.

They always said he should have been in Ravenclaw.

There's no drama. No massive rows in the corridors, or shouting across the classroom. They never really stop caring about each other.

They just realise that there are things they care more about. He needs top grades to enter the Ministry, she needs to do just as well to get on the Healer apprenticeship she wants. Classes begin to take priority, the times when they used to sit and talk become silent study sessions. It's when he rearranges their date for the fourth time in a row, and sees relief in place of the anger he was expecting that he realises just how far things have come.

He ends it soon after that. It's the sort of thing a Gryffindor should do.

"This isn't working. Neither of us can afford distractions now."

He explains, and she accepts his reasoning as a Ravenclaw should. "Maybe we should take a break. At least until the exams are over."

He nods, but doesn't reply. He's not Bill, or Charlie; he isn't good at this. Penelope's eyes soften and she presses a kiss to his cheek. "Take care of yourself, Percy."

"You too," he manages. He knows it's the right decision, for both of them, but when he thinks of how far they've come, and all they've been through he can't help but wonder if academic achievements are worth it.

Maybe he's made a mistake. Maybe he'll regret this. He simply can't know.

He does know he'll never regret loving her.