Prompt: (dialogue) "The main reason Santa is so jolly is because he knows where all the bad girls live."

Jolly Old Saint Nick

"I need your help." Sirius dropped his Muggle Studies book on the table and sat down across from Marlene. "You know a lot about Muggles since you have Muggle relatives and you're friends with Lily. I need you to explain this Santa Claus person to me."

"Santa Claus? The guy who brings gifts to children every Christmas?" Marlene looked at him over her own book, one eyebrow raised.

"Yes, that. I just don't get it. I can't believe anybody would celebrate a holiday where a jolly prowler breaks into your house and leaves gifts." He wrinkled his nose. "Why don't Muggles just exchange gifts the normal way? Why make some creepy guy do it for you?"

"You really don't get it," Marlene said, setting her book down. "Every year, Muggle children write a letter to Santa Claus, a jolly old man who lives at the North Pole, and they ask him to bring them toys for Christmas. He keeps track through the year of all the children who have been good and those who've been bad. Only good children get gifts and those gifts are made by Santa and his elves."

"I see." Sirius tapped his chin thoughtfully. "The main reason Santa is so jolly is because he knows where all the bad girls live."

Marlene rolled her eyes. "I said his name was Santa Claus, not Sirius Black."

"Ooh, she got you good mate," James piped up from his seat by the fire. "You're going to fit in perfectly with us, Mar."

"I'm not sure if I should be flattered or insulted. I suppose I'll thank you for the compliment, only because Lily told me I had to play nice with you boys."

"So then you'd be on the nice list instead of the naughty list? Damn." Sirius ducked as soon as the words left his mouth, barely missing getting hit by Marlene. "Aw, come on, I was only joking. No need for violence."

"You're disgusting!" Marlene stood from her chair and ran up the stairs to the girls' dormitories.

"But... you didn't finish telling me about Santa!" Sirius yelled after her as James tried not to laugh.