Eliezer Yudkowsky - Harry Potter and the Methods of Rationality

“I deduced it from evidence!” said Draco Malfoy’s floating head.

Professor Snape’s head swiveled back to Theodore Nott. “How did you intend to obtain this Stone from inside a magic mirror that could supposedly baffle Dumbledore himself? Answer me at once!”

“We’re going to take the whole mirror and send it back to Flamel,” said Theodore Nott. “It’s not like we want the Stone for ourselves, we just need to stop Dumbledore from stealing it.”

Professor Snape nodded, as though confirming something, and turned his head to look at the other students. “Tell me, have any of you noticed one of the others behaving in an unusual fashion? Especially if there is a peculiar object that they have in their possession, or they can use spells a first-year should not know?” Professor Snape’s right hand now pointed his wand at Susan Bones. “I see that Miss Greengrass and Miss Davis are trying not to look at you, Miss Bones. If there is a mundane explanation, you would be wise to offer it immediately. ”

Susan Bones’s hair turned bright red, though her face didn’t change.

“I suppose there’s not much point keeping it mum any longer,” she said,

“since I’m graduating in two days anyway.”

“Double witches get to graduate six years early?” said Tracey Davis.

“That’s not fair!”

“ Bones is a double witch? ” cried Theodore.

“No, she is Nymphadora Tonks, a Metamorphmagus,” Professor Snape said. “Masquerading as another student is extremely against regulation, as you are well aware, Miss Tonks. It is not too late to expel you from Hogwarts two days before your graduation, which would be a dreadful tragedy—from your perspective, that is. From my perspective it would be hilarious. Now tell me what exactly you are doing here.” “That explains it,” said Daphne Greengrass. “Um, is there actually a Susan Bones, or is the House dying out so they had you secretly—”

The red-haired form of Susan Bones had a palm to her face. “Yes, Miss Greengrass, there’s a real Susan Bones. She only sends me in when you lot are about to get into ridiculous amounts of trouble. Professor Snape, the reason I’m here is because Draco Malfoy was missing, and this lot insisted on trying to find him instead of calling the Aurors. For reasons the real Miss Bones said there was no time to explain to me, which I now realize were stupid. But young students must never go alone, and must be accompanied by a sixth or seventh year at all times. And now we found Draco Malfoy and we can all go back. Please? Before this gets any more ridiculous?”

“ What in Merlin’s name is going on here? ”

“Ah,” said Professor Snape, who was still pointing the wand at the redhaired form of Susan Bones, his other hand still grasping the collar below the disembodied head of Draco Malfoy, standing next to the crumpled form of the Defense Professor. “Professor Sprout, I perceive.” “It’s not what it looks like,” volunteered Tracey Davis.

The short, dumpy form of the Herbology Professor stormed forwards. She had, by this point, drawn her wand, though she wasn’t pointing it at anyone. “ I don’t even know what this looks like! Down wands, all of you, right now! Including you, Professor!”

Distraction. The thought came to Harry with sudden clarity. Whatever he was watching now, from where he stood invisibly and well back of the action, it wasn’t what was really going on , it wasn’t the true thread of the story, it had been arranged . Professor Sprout’s arrival had broken Harry’s suspension of disbelief; things like that didn’t happen just for the sake of comedic coincidence. Someone was deliberately causing all this chaos, but what was the point?

Harry really hoped he hadn’t gone back in time and done this, because it did seem like the sort of thing he would do.

Severus Snape lowered his wand. His other hand unfisted Draco Malfoy. “Professor Sprout,” the Potions Master said, “I am here on the Headmaster’s orders to watch this door. Everyone else present is not supposed

to be here, and I ask you to see them cleared away.”

“A likely story,” snapped Professor Sprout. “Why would Dumbledore set you of all people to guard the door to his playground? It’s not as if he wants to keep the students out, oh no, they need to go in and get stuck in my Devil’s Snare! Susan, dear, you’ve got a communications mirror, don’t you? Use it to call the Aurors.”

The watching Harry nodded to himself. That was the point. The Aurors would take away everyone present at this terribly confusing situation, no excuses accepted, and then the door would be unguarded.

But was Harry meant to go into the forbidden corridor himself? Or watch, to see who finally came once all the others were gone?

A loud fit of hacking and coughing caused everyone to look at where the Defense Professor lay.

“Snape—listen—” said the Defense Professor between coughs.

“Why—Sprout—here—”

The Potions Master looked down.

“Memory Charm—implies—Professor—” The Defense Professor began coughing again.

“ What? ”

And the logic unfolded in Harry’s mind in crystalline dismay, all the steps already suspected, the dreadful realization coming as a repetition

with greater confidence.

Someone had Memory-Charmed Hermione to believe she’d tried to kill Draco.

Only a Hogwarts Professor could have done it without alarm.

So all the true mastermind needed to do was Legilimise or Imperius a Hogwarts Professor.

And the last person anyone would suspect would be the Head of House Hufflepuff.

Snape’s head snapped around, as Professor Sprout raised her wand, and the Potions Master managed to raise a wordless translucent ward between them. But the bolt that shot from Professor Sprout’s wand was a dark brown that produced a surge of awful apprehension in Harry’s mind; and the brown bolt made Severus’s shield wink out before they touched, clipping the Potions Master’s right arm even as he dodged. Professor Snape gave a muffled shriek and his hand spasmed, dropping his wand.

The next bolt that came from Sprout’s wand was a bright red the color of a Stunning Hex, seeming to grow brighter and move faster even as it left her wand, accompanied by another surge of anxiety; and that blew the Potions Master into the door, dropping him motionless to the ground.

By that time pink-haired-Susan-Bones was surrounded by a multifaceted blue haze and she was firing hex after hex at Professor Sprout. Professor Sprout was ignoring the hexes to summon plant tendrils that entangled the younger students as they tried to run, except Draco Malfoy, who had again vanished beneath his invisibility cloak.

Not-Susan-Bones stopped casting hexes. She leveled her wand, took a deep breath, and cried aloud an incantation that sent golden worms of light chewing into the shield around Professor Sprout. At that the Herbology Professor turned to face not-Susan, her expression vacant, a new set of plant tentacles rising in the air behind her. Those stalks were a darker green, and seemed to have shields of their own.

Harry Potter murmured to the seemingly empty air, “Attack Sprout.

Help Bones. Nonlethal only.”

“Yes, my lord,” whispered Lesath Lestrange beneath Harry’s Cloak of Invisibility, and the fifth-year Slytherin’s presence moved off toward the fight.

Harry looked down at at his own hands, and saw with a jolt of unpleasant shock that his Disillusionment Charm wasn’t as complete as it had been before. There were hints of distortion in the air, each time Harry moved…

Slowly, Harry stepped backward, until he came to a corner, and ducked behind a wall. Then he took out his communications mirror… which was blank and jammed. Of course. Harry levitated the mirror to where he could use it to see around the corner, and watch the end of the… distraction? What was happening, why?