Your sister
Our story starts in Vernon's house, he has invited his girlfriend Petunia over.
Petunia said, "Why am I here on a Sunday?"
Vernon told her, "I wanted to ask you something without your parents around."
Petunia gasped. "Vernon, we hardly know each other!"
Vernon shook his head. "I'm not ruddy proposing, my dear. I just want to ask about your sister."
Petunia frowned. "Has she said or done something to you?"
Vernon grunted. "Not at all, but she has visited this very house once."
Petunia's face turned as white as a sheet. "Well, I cannot tell you how sorry I am for that. She's a freak and so is her boyfriend."
Vernon asked, "What do you mean by freak?"
Petunia muttered, "N-Nothing, just don't associate with them. She hates me anyway."
Vernon stated, "Now, I doubt that's true. I will not bring her up again though as you very clearly aren't pleased with me for doing so.".
Petunia responded, "Thank you."