DISCLAIMER: Harry Potter is not mine, and someone might have already used a similar plot, but I came up with this myself.
In the hall.
"Move it, mudblood."
"Pureblood."
"That's the best you can do? It's hardly an insult."
"Sure it is."
"Huh. Explain."
"Nope."
"No? What the heck, Granger?"
"Malfoy."
"Was that an 'insult' too?"
"Yes."
"Why?"
"Not telling."
"Granger!"
"What?"
"Don't walk away, mudblood, I'm trying to talk to you."
"What, the great Draco Malfoy, trying to talk to Hermione Granger? Impossible."
"Granger! Slow down!"
"Naw, don't feel like it."
"You will listen when I speak to you."
"Fuck off."
"Did you just say 'fuck'?"
"Yeah. What's fucking wrong with that?"
"Granger, are you sick?"
"Malfoy, why would you care?"
"Because then I might loose my sparring partner."
"OK, touching. And why would I be sick?"
"I don't know of any Granger who cusses."
"My father does when he stubs his toe hard."
"I don't know your father, and I didn't know of his cursing."
"What ever."
"Granger, are you certain you're feeling alright?"
"Hmph."
"If you're feeling fine, tell me why being pureblood is an insult."
"I wouldn't tell you that if I were fine."
"You got me there. And you're not feeling fine, so you'll tell me."
"Since when does it matter what I think of you?"
"This isn't about you, this is about me being awesome in all respects."
"So if I told you what was wrong with your blood you'd get a blood transfusion?"
"No. I'd make sure no one else knew about it."
"Figures. Coward."
"I'm not a coward!"
"Then prove it."
"I want something in return."
"I'd tell you about your blood and bloody Malfoy-ness."
"So how shall I prove my bravery?"
"In the Great Hall at dinner, scream 'I love fucking Hermione bloody Granger, and now you all know it and I can't take it anymore, and I want to ask her out. And I she declines, I'll run around the teachers' table twenty times in nothing but a fig leaf.'"
"Why you?"
"Because you most openly despise Harry, Ron, and me, and something tells me Harry and Ron would be angry about me setting you up with them."
"OK. Deal."
"Great. And I'll decline the date."
"Less good…"
"Are you chickening out?"
"No!"
"Good. See you at dinner."