Harry Potter and the Methods of Rationality

"The enemy knew perfectly well that you'd turn back time to check what really happened to Hermione, especially since the troll getting into Hogwarts at all tells us that somebody can fool the wards." Harry shut his eyes, thinking harder, trying to put himself into the enemy's shoes. Why would he, or his dark side, have done something like - "We're meant to conclude that the enemy has control of what the wards tell us. But that's actually something the enemy can only do with difficulty, or under special conditions; they're trying to create a false appearance of omnipotence." Like I would. "Later, hypothetically, the wards show Professor Sinistra killing someone. We think the wards are just being fooled again, but really, Professor Sinistra was Legilimized and she did do it."

"Unless that is precisely what the Dark Lord expects us to think," said Severus Snape, his brow furrowed in concentration. "In which case he does have control of the wards, and Professor Sinistra will be innocent."

"Does the Dark Lord really use plots with that many levels of meta -"

"Yes," said Dumbledore and Severus.

Harry nodded distantly. "Then this could be a setup to either make us think the wards are telling the truth when they're lying, or a setup to make us think the wards are lying when they're telling the truth, depending on what level the enemy expects us to reason at. But if the enemy is planning to make us trust the wards - we would have trusted the wards anyway, if we'd been given no reason to distrust them. So there's no need to go to all the work of framing Professor Quirrell in a way that we would realize we were intended to discover, just to trick us into going meta -"

"Not so," said Dumbledore. "If Voldemort has not fully mastered the wards, then the wards had to believe that some Professor's hand was at work. Else they would have cried out at Miss Granger's injury, and not only upon her death."

Harry reached up a hand and rubbed at his brow, just beneath his hair.

Okay, serious question. If the enemy is that smart, why the heck am I still alive? Is it seriously that hard to poison someone, are there Charms and Potions and bezoars which can cure me of literally anything that could be slipped into my breakfast? Would the wards record it, trace the magic of the murderer?

Could my scar contain the fragment of soul that's keeping the Dark Lord anchored to the world, so he doesn't want to kill me? Instead he's trying to drive off all my friends to weaken my spirit so he can take over my body? It'd explain the Parselmouth thing. The Sorting Hat might not be able to detect a lich-phylactery-thingy. Obvious problem 1, the Dark Lord is supposed to have made his lich-phylactery-thingy in 1943 by killing whatshername and framing Mr. Hagrid. Obvious problem 2, there's no such thing as souls.

Though Dumbledore also thought that my blood was a key ingredient in a ritual to restore the Dark Lord's full strength, which would require keeping me alive until then... now there's a cheery thought.

"Well..." Harry said. "I'm sure of one thing."

"And that is?"

"Neville needs to be taken out of Hogwarts now. He's the obvious next target and no first-year student can survive this level of offense. We're lucky Neville wasn't assassinated yesterday evening, the enemy doesn't have to wait until we're finished mourning to make their next move." Why didn't the enemy strike while we were distracted?

Dumbledore exchanged glances with Severus, and then with the suddenly tight expression of Professor McGonagall. "Harry," said the old wizard, "if you send all your friends away yourself, that is just the same as if Voldemort -"

"I will be fine I can do without Neville for a couple of extra months it's not like you were planning to make my friends stay here over the summer and that is just plain not sufficient justification to let him get killed! Professor McGonagall -"

"I quite agree," said the Scottish witch. She frowned. "I extremely agree. I agree to the point where... I'm having some trouble figuring out how to express this, Albus..."

"To the point where you're going to haul him out of there yourself, regardless of what anyone else says, because it's no excuse to say you were only following orders if Neville gets killed?" Harry said.

Professor McGonagall closed her eyes briefly. "Yes, but surely there ought to be some way to be responsible without threats of unilateral action."

The Headmaster sighed. "No need. Go, Minerva."

"Wait," the Potions Master said, just as Professor McGonagall, moving rather swiftly, was taking a pinch of green dust from the Floo-vase. "We should not call attention to the boy, as the Headmaster called attention to the Weasley twins. It would be wiser, I think, if Mr. Longbottom's grandmother took him from Hogwarts. Let him stay in his Common Room for now; the Dark Lord does not seem able to act so openly."

There was another long exchange of glances among the four, and finally Harry nodded, followed by Professor McGonagall.

"In that case," said Harry, "I'm sure of one other thing."

"And that is?" said Dumbledore.

"I very much need to visit the washroom, and I would also like to change out of these pyjamas."

"By the way," Harry said as he and the Headmaster emerged from Floo into the empty office of the Ravenclaw Head of House. "One last quick question I wanted to ask just you. That sword the Weasley twins pulled out of the Sorting Hat. That was the Sword of Gryffindor, wasn't it?"

The old wizard turned, face neutral. "What makes you think that, Harry?"

"The Sorting Hat yelled Gryffindor! just before handing it out, the sword had a ruby pommel and gold letters on the blade, and the Latin script said Nothing better. Just a hunch."

"Nihil supernum," said the old wizard. "That is not quite what it means."