Eliezer Yudkowsky - Harry Potter and the Methods of Rationality

“Students serving detention,” Filch said, loudly. “They’re to help you search the Forest for… whatever’s been eating ’em.”

“The Forest? ” gasped Tracey. “We can’t go in there at night!”

“That’s right,” said Filch, turning from Hagrid to glare at them. “It’s into the Forest you’re going, and I’m much mistaken if you’ll all come out in one piece.”

“But—” said Tracey. “There’s werewolves, I’ve heard, and vampires, and everyone knows what happens when there’s a girl and a werewolf and a vampire all at the same time!”

The huge half-giant was frowning. “Argus, I ’ad in mind you an’ maybe a few seventh-years. ’Ere’s not much point in bringing along help if I’m to watch over ’em the whole time.”

Argus’s face lit with cruel satisfaction. “That’s their lookout, isn’t it? Should’ve thought of them werewolves before they got in trouble, shouldn’t they? Send them out alone. I shouldn’t be too friendly to them,

Hagrid. They’re here to be punished, after all.”

The half-giant gave a massive sigh (it sounded like a normal man having all the air driven out of his lungs by a Bludgeoning Hex). “Yeh’ve done yer bit. I’ll take over from here.”

“I’ll be back at dawn,” said Filch, “for what’s left of them,” he added nastily, and he turned and started back toward the castle, his lamp bobbing away in the darkness.

“Right then,” said Hagrid, “now, listen carefully, ’cause it’s dangerous what we’re gonna do tonight an’ I don’ want no one takin’ risks. Follow me over here a moment.”

He led them to the very edge of the Forest. Holding his lamp up high he pointed down a narrow, winding earth track that disappeared into the thick black trees. A light breeze blew over Draco’s head as he looked into the Forest.

“There’s summat in there that’s bin eatin’ unicorns,” the huge man said.

Draco nodded; he distantly remembered hearing something along those lines a couple of weeks ago, toward the end of April.

“Did you call us to track down a trail of silvery blood to a wounded unicorn?” Tracey said excitedly.

“No,” said Draco, though he managed to stop the reflexive sneer. “Filch gave us the detention note at lunch today, at noon. Mr. Hagrid wouldn’t wait that long to find a wounded unicorn, and if we were looking for something like that, we’d look in the day when it’s bright. So,” Draco held up a finger, like he’d seen Inspector León do in plays, “I infer that we’re looking for something that only comes out at night.”

“Aye,” said the half-giant, sounding thoughtful. “Yer not what I expected, Draco Malfoy. Not what I expected at all. An’ you’d be Tracey

Davis, then. I’ve heard of yeh. One of poor Miss Granger’s lot.” Rubeus Hagrid looked over at the two older Slytherins, peering at them in the light of his glowing umbrella. “An’ who’d yeh be, again? Don’t remember seeing much of yeh, boy.”

“Cornelia Walt,” said the witch, “and this is Yuri Yuliy,” indicating the Slavic-looking boy who’d spoken of Durmstrang. “His family is visiting from the Ukrainian lands, so he’s in Hogwarts just for the year.” The older boy nodded, a faintly contemptuous cast on his face.

“This is Fang,” Hagrid said, indicating the dog.

The five of them set off into the woods.

“What could be killing unicorns?” Draco said after they’d walked for a few minutes. Draco knew a bit about Dark creatures, but he couldn’t remember anything that was said to prey on unicorns. “What sort of creature does that, does anyone know?” “Werewolves!” said Tracey.

“Miss Davis?” Draco said, and when she looked at him, he silently pointed a finger up at the moon. It was waxing gibbous, but not yet full.

“Oh, right,” said Tracey.

“No weres in the Forest,” said Hagrid. “They’re plain wizards most o’ the time, ’member. Couldn’t be wolves either, they’re not near fast enough ter catch a unicorn. Powerful magical creatures, unicorns are,

I never knew one ter be hurt before.”

Draco listened to this, thinking about the puzzle almost despite himself. “Then what is fast enough to catch a unicorn?”

“Wouldn’t ’ave been a matter of speed,” Hagrid said, giving Draco an indecipherable glance. “Ere’s no end ter the ways that creatures hunt. Poison, darkness, traps. Imps as can’t be seen or heard or remembered, even while they’re eatin’ yer face. Always summat new an’ wonderful to learn.” A cloud passed over the moon, casting the forest into shadow lit only by the glow of Hagrid’s umbrella.

“Meself,” Hagrid continued, “I think we might ’ave a Parisian hydra on our ’ands. They’re no threat to a wizard, yeh’ve just got to keep holdin’ ’em off long enough, and there’s no way yeh can lose. I mean literally no way yeh can lose so long’s yeh keep fightin’. Trouble is, against a Parisian hydra, most creatures give up long before. Takes a while to cut down all the heads, yeh see.”

“Bah,” said the foreign boy. “In Durmstrang we learn to fight Buchholz hydra. Unimaginably more tedious to fight! I mean literally, cannot imagine. First-years not believe us when we tell them winning is possible!

Instructor must give second order, iterate until they comprehend.”

They walked for nearly half an hour, deeper and deeper into the Forest, until the path became almost impossible to follow because the trees

were so thick.

Then Draco saw it, thick splashes on the roots of trees, gleaming a brighter color beneath the moonlight. “Is that—”

“Unicorn’s blood,” Hagrid said. The huge man’s voice was sad.

In a clearing ahead, visible through the tangled branches of a great oak, they saw the fallen creature, splayed beautiful and sad upon the ground, the dirt around her shining moon-silver with pooled blood. The unicorn was not white, but pale blue, or appearing so beneath the moon and night sky. Her slender legs stuck out at odd angles, obviously broken, and her mane spread across the dark leaves, green-black but with a sheen like pearls. On her flank was a small white shape like a starburst, a center surrounded by eight straight rays. Half her side had been ripped away, the edges ragged like the marks of teeth, bones and inner organs exposed.

A strange choking sensation rose in Draco’s throat.

“That’s ’er,” Hagrid said, his sad whisper as loud as a normal man’s voice. “Just where I found ’er this mornin’, dead as a dead doorknob. She is—was—the first unicorn I e’er met in these woods. I called ’er Alicorn, not that it matters ter ’er any more, I s’pose.”

“You named a unicorn Alicorn,” said the older girl. Her voice was a bit dry.

“But she doesn’t have wings,” Tracey said.

“An alicorn’s a unicorn’s horn,” Hagrid said, now louder. “Don’t know where yeh all started thinking it meant a unicorn with wings, ’ere’s no such thing I ever heard. It’s just like naming a dog Fang,” indicating the huge wolf-like dog that barely came to his knees. “What’d you have called ’er? Hannah, or some such? I gave ’er a name as would’ve meant summat ter ’er. Common courtesy, I call it.”

Nobody said anything to this, and after a further moment, the huge man gave a sharp nod. “We’ll start our search from ’ere, the last place it struck. We’re gonna split inter two parties an’ follow the trail in diff’rent directions. Yeh two, Walt and Yuliy—yeh’ll go that way, and take Fang. There’s nothin’ that lives in the Forest that’ll hurt yeh if yer with Fang. Send up green sparks if yeh find summat interestin’, an’ send up red sparks if anyone gets in trouble. Davis, Malfoy, with me.”