Harry Potter and the Methods of Rationality

"Both of you stop being silly," Professor McGonagall said in her firm Scottish accent (it was strange how much that helped). "Mr. Potter, hold out your wand so that Miss Granger's fingers can touch it. Miss Granger, repeat after me. Upon my life and magic -"

Harry did as he was bid, thrusting his wand forward to touch Hermione's fingers; and then Hermione's faltering voice said, "Upon my life and magic -"

"I swear service to the House of Potter -" said Professor McGonagall.

And Hermione, without waiting for any further instructions, said, the words spilling out of her in a rush, "I swear service to the House of Potter, to obey its Master or Mistress, and stand at their right hand, and fight at their command, and follow where they go, until the day I die."

All those words had been blurted out in a desperate gasp before Harry could have thought or said anything, if he'd been mad enough to interrupt.

"Mr. Potter, repeat these words," said Professor McGonagall. "I, Harry, heir and last scion of the Potters, accept your service, until the end of the world and its magic."

Harry took a breath and said, "I, Harry, heir and last scion of the Potters, accept your service, until the end of the world and its magic."

"That's it," said Professor McGonagall. "Well done."

Harry looked up, and saw that the entire Wizengamot, whose existence he'd forgotten, was staring at them.

And then Minerva McGonagall, who was Head of House Gryffindor even if she didn't always act like it, looked up high above at where Lucius Malfoy stood; and she said to him before the entire Wizengamot, "I regret every point I ever gave you in Transfiguration, you vile little worm."

Whatever Lucius was about to say in reply was silenced by a tap of the short rod in Dumbledore's hand. "Ahem!" said the old wizard from his podium of dark stone. "This session has carried on quite considerably, and if it is not dismissed soon, some of us may miss their entire luncheon. The law of this matter is clear. You have already voted on the terms of the bargain, and Lord Malfoy cannot legally decline it. As we have far exceeded our allotted time, I now, in accordance with the last decision of the survivors of the eighty-eighth Wizengamot, adjourn this session."

The old wizard tapped the rod of dark stone three times.

"You fools!" shouted Lucius Malfoy. The white hair was shaking as though in a wind, the face beneath was pale with fury. "Do you think you'll get away with what you've done today? Do you think that girl can try to murder my son and escape unscathed?"

The toad-like pink-makeup woman, whose name Harry could no longer remember, was standing up from her seat. "Why, of course not," she said with a sickening smile. "After all, the girl is still a murderess, and I think the Ministry shall be watching her affairs quite closely - it hardly seems wise that she should be allowed to wander the streets, after all -"

Harry was fed up at this point.

Without waiting to listen, Harry turned on his heel and strode forward in long steps toward -

The horror only he could truly see, the absence of color and space, the wound in the world, above which floated a tattered cloak; most imperfectly guarded by a running moonlit squirrel and fluttering silver sparrow.

His dark side had also noticed, when it was looking through the entire room for anything that could possibly be used as a weapon, that the enemy had been foolish enough to bring a Dementor into Harry's presence. That was a powerful weapon indeed, and one that Harry might wield better than its supposed masters. There had been a time in Azkaban when Harry had told twelve Dementors to turn and go, and they had gone.

The Dementors are Death, and the Patronus Charm works by thinking about happy thoughts instead of Death.

If Harry's theory was correct, that one sentence would be all it took to pop the Aurors' Patronus Charms like a soap bubble, and ensure that nobody within reach of his voice could cast another one.

I am going to cancel the Patronus Charms and prevent any more Patronuses from being cast. And then my Dementor, flying faster than any broomstick, is going to Kiss everyone here who voted to send a twelve-year-old girl to Azkaban.

Say that, to set up the if-then expectation, and wait for people to understand and laugh. Then speak the fatal truth; and when the Aurors' Patronuses winked out to prove the point, either people's anticipations of the mindless void, or Harry's threat of its destruction, would make the Dementor obey. Those who had sought to compromise with the darkness would be consumed by it.

It was the other solution his dark side had devised.