Eliezer Yudkowsky - Harry Potter and the Methods of Rationality

Another unicorn lay on the ground, surrounded by a slowly widening pool of silver blood, the edge of the blood creeping across the ground like spilled mercury. Her coat was purple, like the color of the night sky, her horn exactly the same twilight color as her skin, her visible flank marked by a pink star-blotch surrounded by white patches. The sight tore at Draco’s heart, even more than the other unicorn because this one’s eyes were staring glassily right at him, and because there was a—

—blurring, twisting form—

—feeding on an open wound on the unicorn’s side, like it was drinking from it—

—Draco couldn’t understand, somehow couldn’t recognize what he was seeing—

— it was looking at them.

The blurring, seething, unrecognizable darkness seemed to turn to regard them. A hiss came from it, like the hiss of the deadliest snake which ever had existed, something more dangerous by far than any Blue Krait.

Then it bent back over the wound in the unicorn, and continued to drink.

The mirror was in Draco’s hand, and it remained lifeless as his finger mechanically tapped at the surface, over and over.

Tracey was holding her wand now, saying things like “Prismatis” and “Stupefy” but nothing was happening.

Then the seething outline rose up, like a man rising to his feet only not so; and it seemed to scuttle forward, moving with a strange half-jump across the dying unicorn’s legs, approaching the two of them.

Tracey tugged at his sleeve and then turned to run, run from something that could hunt down unicorns. Before she could take three steps there came another terrible hiss, burning his ears, and Tracey fell to the ground and did not move.

Somewhere in the back of his mind, Draco knew that he was about to die. Even if the Auror checked his mirror this very instant, there was no way anyone could get here fast enough. There was no time.

Running hadn’t worked.

Magic hadn’t worked.

The seething outline came closer, while Draco tried, in his last moments, to solve the riddle.

Then a blazing silver ball of light plunged out of the night sky and hung there, illuminating the forest as bright as daylight, and the seething outline leapt backwards, as though in horror of the light.

Four broomsticks plunged out of the sky, three Aurors with bright multicolored shields and Harry Potter holding his wand aloft, seated behind Professor McGonagall within a larger shield.

“Get out of here!” roared Professor McGonagall—

—an instant before the seething thing gave forth another terrible hiss, and all the shielding spells winked out. The three Aurors and Professor McGonagall fell off their broomsticks and dropped heavily to the forest floor, lying motionless.

Draco couldn’t breathe, the most intense fear he’d ever felt in his life gripping all through his chest, sending tendrils around his heart.

Harry Potter, who had remained untouched, silently guided his broomstick toward the ground—

—and then leapt off to stand between Draco and the seething outline, interposing himself like a living shield.

“Run!” said Harry Potter, turning his head half-back to look at Draco. The silver moonlight gleamed on his face. “Run, Draco! I’ll hold it off!”

“You can’t fight that thing alone!” Draco cried aloud. A nausea was in his stomach, a churning sensation that, looking back in memory, seemed both like and unlike a sense of guilt, as though it had the sensations but not quite all of the emotion.

“I must,” Harry Potter said grimly. “Go!”

“Harry, I—I’m sorry, for everything—I” Though later, looking back, Draco couldn’t quite remember what he’d meant to apologize for, maybe it’d been that he was planning to overthow Harry’s conspiracy, all that time ago.

The seething figure, now seeming blacker and more terrible, rose up into the air, hovering off the ground.

“GO!” shouted Harry.

Draco turned and fled headlong into the woods,with the branches whipping at his face. Behind him, Draco heard another terrible hiss, and Harry’s voice rising, crying something that Draco couldn’t make out from the distance; Draco turned his head for only an instant to look back, and in that moment ran into something, hitting his head HARD, and blacked out.

Harry held a tight grip on his wand, a Prismatic Sphere glowing around him. He stared levelly at the seething, blurring form in front of him, and said, “What on Earth are you doing?”

The seething blurs resolved, reformed, relaxed back into a hooded form. Whatever concealment had been at work—a device rather than a Charm, Harry guessed, since the magic had been able to affect him—had prevented his mind from recognizing the shape or even that the shape was human. But it hadn’t prevented Harry from recognizing the sharp sense of doom.

Professor Quirrell stood straight with silver blood all down the front of his enshrouding black cloak, and gave a sigh, looking at the fallen forms of three Aurors, Tracey Davis, Draco Malfoy, and Professor McGonagall. “I had honestly thought,” Professor Quirrell murmured, “that I jammed that mirror without alarm. What were two first-year Slytherins doing alone in the Forbidden Forest? Mr. Malfoy has more sense than this… What a fiasco.”

Harry didn’t answer. The sense of doom was as strong as Harry could ever remember feeling it, a feeling of power in the air so great that it was almost tangible. Some part of him was still viscerally shocked at how fast the shields surrounding the Aurors had been torn apart. He almost hadn’t been able to see the successive lashes of color which had torn away the shields like tissue paper. It made the duel Professor Quirrell had fought against the Auror in Azkaban look like a mockery, a child’s game—though Professor Quirrell had claimed, then, that if he’d fought for real the Auror would have been dead in seconds; and Harry knew now that this was also true.

Just how high did the power ladder go?

“I take it,” Harry said, managing to keep his voice steady, “that your eating unicorns has something to do with why you’ll get fired from the Defense Professor position. I don’t suppose you’d care to explain in considerable detail?”

Professor Quirrell looked at him. The almost tangible sense of power in the air seemed to diminish, drawing back into the Defense Professor. “I shall indeed explain myself,” the Defense Professor said. “I need to cast a few Memory Charms first, and then we may go off and discuss it, for it would not be wise for me to stay. You will return to this time later, as I know.”

Harry willed himself to be able to see through the Cloak he had mastered; and knew that another Harry stood beside him, hidden by his own Deathly Hallow. Harry then told his Cloak to hide himself from himself once more, and it did; being able to perceive your future self meant having to match the memory later.

Harry’s own voice said, then, sounding strange in present-Harry’s ears, “He has a surprisingly good explanation.”

Present-Harry remembered the words as best he could. Nothing more was said between them.

Professor Quirrell walked to Draco’s form, and chanted the spell of the False Memory Charm. The Defense Professor stood there for perhaps a minute, seemingly lost to the world.

Harry had been studying Obliviations, these last couple of weeks— though he couldn’t have helped cast the spells, unless he was willing to exhaust himself almost completely, and for some reason they wanted an Auror to lose every single life memory involving the color blue. But Harry had some idea, now, of the concentration which the far more difficult False Memory Charm entailed. You had to try to live the other person’s entire life inside your own head, at least if you wanted to create the False Memories with less than a sixteen-to-one slowdown as you separately crafted sixteen major tracks of memory. It might have been quiet, there might have been no outward sign; but Harry knew something of the difficulties now, and he knew to be impressed.