Harry Potter and the Methods of Rationality

"Yes or no. Please answer immediately."

"Ah - there's the Floo -"

"She's not in her office," Harry said. "Do you have any other way of reaching her. Yes or no."

"Young man, I insist that you -"

Harry's brain flagged this as I'm talking to NPCs again and he spun on his heel and dashed back for the broomstick.

"Stop!" cried Madam Pince, bursting too late from the doors as Harry and the Weasley twins shot off again, out of the librarian's sight. The pressure in Harry's mind still rising, like a physical hand squeezing his chest, he had to find Hermione and he had no other notion of where she could be, unless it was the witches' dorms in the Ravenclaw tower and that he couldn't enter. Searching all of Hogwarts bordered on a mathematical impossibility, there probably was no continuous flight path that entered all the rooms at least once - why hadn't he thought to demand for Hermione and Neville and him to be given a set of those neat little mirrors the Aurors used to communicate -

The realization that he was being stupid hit Harry like a blow to the stomach. He didn't need mirrors to send a message, he hadn't needed mirrors since January. Harry slowed the broomstick to a halt in midair of a hallway, his wand already coming into his hand, the driving will to protect Hermione Granger rising to the front of his mind like a sun of silver fire and flowing down his arm as he cried

"EXPECTO PATRONUM!"

and the blazing white humanoid burst into existence like a nova, the Weasley twins' voices crying aloud in shock.

"Tell Hermione Granger - that there's a troll loose in Hogwarts - it could be hunting for her - she needs to get into direct sunlight, now!"

The silver figure turned as though it was departing, and then vanished.

"Merlin's underpants," breathed Fred or George.

The silver outline blasted back into the world, and said in the strange outside version of Harry's own voice, "Hermione Granger says," the blazing figure's voice became higher-pitched, "AHHHHHHHHH! "

Time seemed to fracture, like everything was moving very quickly and slowly at the same time. A desperate impulse to accelerate the broomstick, fly at its maximum speed, only Harry didn't know where -

"If you know where she is," Harry shouted to the blazing humanoid figure, staring into it as though it were a sun, "then take me to her!"

The silver blaze moved and Harry accelerated after it, the Weasley twins giving out high-pitched shrieks behind him as he fired through the air like a cannonball, moving faster than sanity, he didn't focus on the walls whizzing past him or how fast he was moving, just followed the silver light through corridors and flying up staircases and blitzing through doors that Fred or George cried desperate incantations to open and it was all still taking too much time, somewhere deep inside Harry felt like he was sinking through molasses as windows and portraits shot past.

The broomstick screamed through a final turn that whacked one of the Weasley twins against the wall not quite as hard as a Bludger would hit, and then they followed the brilliant Patronus through an open space in the ceilings, blasting up and upwards, rising past one floor and then another in less than a breath.

His Patronus slowed to a halt (Harry braking hard in response) just as they reached the level of a wide-open floor space that that spread out until it escaped the ceiling and turned into an outdoor terrace, a spread of tiled marble open to the air and sky -

Chapter 89: Time Pressure, Pt 2

Cool blue fires clung to the floor in small masses, surrounding a blazing pool that seemed to burn with a deadlier, hotter blue.

In one narrow circle the marble tiles were scorched and shattered by some explosive spell that only the most prodigious of first-year witches could have cast, with the last of her strength.

On the terrace, still moving beneath the open sunlight, stood a great lumpy creature of dull granite-grey. Body like a boulder with small bald head perched on top like a stone, short legs thick as tree trunks with flat, horny feet. One hand held a tremendous stone club as long and as wide as an adult human, and the other hand held

The Weasley twins screamed.

Harry's Patronus shattered.

The troll snorted and spun around to face them, dropping

into the red pool that had spread out beneath its feet, raising its club high.

Then a Weasley cried an incantation and the club was torn from the troll's hand, smashed into its face so hard it drove the troll back for one of its steps, a blow that might have killed a Muggle. The troll gave a bellow of anger, its nose squashed and blood-spattered, and then the nose straightened once more, regenerated. The troll grabbed with both hands for the club, which shot away through the air but only barely dodged the grab.

"Lead it away, keep it off me," said a voice.

The levitated club moved backwards from the troll, from the terrace onto the wide-open floor beneath the ceiling; and the troll made a great prodigious leap that almost brought the club into its hands. Then the troll made another great leap as the club moved to one side; and the broomstick moved forwards and Harry jumped off and ran towards where Hermione Granger was lying in a pool of her own blood with her legs eaten away to the upper thighs.