Another bit of unplanned foreshadowing, Seamus on Percy: "I bet Percy wishes he could posess the twins and make them behave properly. Thats how it works right? Theyd have to do whatever he wanted. They let the Head Boy and girl use crucio but no ones suggested letting prefects use imperius yet."

Percy later (Y3, I think, but I can't remember exactly when) cast a coercion spell on Ron to force him to apologize to Draco for something he'd said.