Disclaimer: I don't own anything recognisable. I hope you enjoy. This is just a very brief introduction to how they met and became friends. It's meant as a sort of introduction instead of a full chapter.
There was a three year age difference between them, in the muggle world that would be strange. 14 year olds hanging out with 11 year olds. It would be considered even stranger as the elder of the two was a boy, the younger a girl. People would think there was something strange about the relationship.
Now both of the students were alone, nearly constantly. No one wanted to be friends with Percy Weasley who they knew was a shoe in for prefect. He preferred to follow the rules but he had good reasons behind his actions. He was always the first one to stop someone from bullying another person. Usually that tended to make him the target, especially from his twin brothers.
Harry on the other hand, fought to not be a victim. She had spent most of her life being cruelly mocked and tormented that she would be damned now that she was home, in a world where she should belong, to allow it to continue. So she fought, it didn't help that a group of Gryffindors, the moment she arrived had chosen to make her there target for the year.
They likely never would have noticed each other except one day that she was getting her arse kicked by a group of students, Percy broke it up and got them to leave her alone. The other students left, leaving him to check her over. "You okay," he asked worriedly helping her up.
She nodded breathing deeply. She was as okay as she ever was though she was in pain at the moment. "Thanks, I really appreciate that."
Percy was shocked, no one ever thanked him for stepping in. "Aren't you pissed off that I interrupted?"
Harry couldn't help it but she looked at him like he was an idiot. "You just saved me from having my arse handed to me...again. I can fight one on one, even two on one but I cannot fight four on one especially because two of them were second years. I'm only 11 and I only just got to Hogwarts, I can't defend myself from that. You saved me from having to go to the infirmary so thanks."
He shook himself from his stupor, he of course knew she was losing the fight but at the same time, people still tended to get annoyed at him. "No problem," he said sending an episkey to a cut causing her face to light up as she watched it heal. She loved magic.
"Can you show me how to do that, it would come right useful."
He nodded surprised that she wanted to learn it from him, "sure but its definitely above an OWL year spell, it will take some practice."
She looked at him seriously, "I will need it," She said without hesitation, he realized where he knew her from, she had been one to get in a lot of trouble and even more fights. He had a feeling that she would definitely need it. "Are you the twin's brother?"
He couldn't quite stop the cringe at that statement. "Yeah."
She scowled slightly though not at him. "Your brothers can be right bastards."
Percy was use to everyone praising his brothers so the statement shocked him, most people loved his brothers. They were fun-loving pranksters. Outgoing, friendly, happy. Everyone loved them and loved their pranks as long as they were not the ones being targeted. "Yeah they can be." He glanced around knowing he could get into a lot of trouble for this but something was telling him to help the girl. "I can maybe teach you a couple hexes that will give you one up on them?"
Harry looked at him shocked, a look of absolute amazement on her face, "You are so fuckin cool."
No one had ever called Percy cool before, he wasn't sure how to take it.