Will didn't particularly mind Umbridge stirring up trouble at school. If she didn't cause trouble now, it would be harder to kick her out of Hogwarts later.
But interrupting his studies? That was a little harder to forgive. In the spirit of treating everyone equally, Will felt entitled to cast an Unforgivable Curse on Umbridge.
"Umbridge," Professor McGonagall said with a frown, "if you cannot sit here quietly, I must ask you to leave at once. Learning the Vanishing Spell carries risks, and I will not have Hogwarts students injured because of a distraction like this."
Umbridge still hadn't worked out why so many Slytherin students were glaring at her. Even Malfoy looked displeased with her. She had only interrupted McGonagall's lesson, and Slytherin and Gryffindor had never got along.
She didn't dwell on it. Instead, she challenged Professor McGonagall. "Professor McGonagall, I interrupted you precisely because the Vanishing Spell is so dangerous. How can you teach students such a dangerous spell?"
Professor McGonagall looked at her as though she were an idiot. "It appears on their O.W.L. exams. Would you prefer they all lose marks?"
"Oh, you mustn't put words in my mouth," Umbridge said dramatically. "It's just that the Vanishing Spell hasn't appeared on the O.W.L. exams for the past two years, has it? I wonder whether your lessons might benefit from a little adjustment."
"I suggest you leave the classroom," Professor McGonagall said sternly. "I will not allow you to waste my students' lesson time."
"Very well. Very well." Umbridge looked furious. "You will receive the results of my investigation within ten days."
"I can hardly wait. Now, please leave."
With Umbridge gone, the whole room seemed more comfortable. Professor McGonagall turned to Will. "Peace at last. But we haven't much time left, and I need to