Harry Potter and the Methods of Rationality

Then they all heard the sound of more feet approaching from the corridor. The fourth-year Gryffindors and Slytherins had just been let out of Potions class.

The footsteps pattered past, and diminished and faded, and the bully didn't do anything. For a moment Susan felt an instant of relief -

Then another, smaller group of footsteps approached.

The bully still didn't do anything, as the footsteps went past.

That happened a few more times.

And then, as there approached the faintly audible sound of one last set of footsteps, the seven girls heard the bully's voice saying, clear and cold and quiet, "Protego".

Someone did gasp then, though fortunately very very quietly. If they couldn't get in even a single shot -

The bullies were learning already, Susan realized, she hadn't expected S.P.H.E.W. to be able to do this very often before the bullies caught on - but - Hermione had already defeated three bullies - and the school had been buzzing with speculation about Salazar Slytherin's ghost, yesterday -

He's expecting us!

Susan would have whispered to give up, to abort the plan, only there was no way to convey a message to -

"Silencio," said the bully in a soft, deliberate voice with his wand pointed toward the corridor, the blue haze of his Shielding Charm shimmering around him. "Accio victim."

When the fourth-year boy came into their field of vision he was dangling upside down as if an invisible hand were holding him high by one leg, his red-trimmed robes beginning to slide down his thighs to reveal the pants beneath. His mouth was opening and closing helpessly, no sound coming out.

"I suppose you're wondering what's going on," the seventh-year Slytherin said in a quiet, cold voice. "Don't worry. It's so simple even a Gryffindor could understand."

With that, the Slytherin's left hand formed a fist and drove hard into the Gryffindor's belly. The fourth-year boy's body jerked around frantically, but still no words left his mouth.

"You're my victim," said the older Slytherin. "I'm a bully. I'm going to beat you up. And we'll see if anyone stops me."

It was at that moment that Susan realized it was a trap.

And in almost the same moment, there rang out the mighty and high-pitched voice of a young girl, crying, "Stop, evildoer! Finite Incantatem!"

Lavender, thought Susan, agonized. The Gryffindor girl had volunteered to be a distraction, while the rest of them executed a flank attack from where the bully wouldn't expect it, that had been the plan, only now -

"In the name of Hogwarts," cried Lavender's voice, though they couldn't see her, "and in the name of heroines everywhere, I command you to let go of that EEK!"

"Expelliarmus," said the bully. "Stupefy. Accio stupid heroine."

When Lavender floated into their vision, dangling by one foot and unconscious, Susan blinked; the girl was dressed in a bright crimson-and-gold skirt and blouse, instead of her usual Hogwarts robes.

The bully was also giving the girl's upside-down body an odd look, and then he pointed his wand at her and said "Finite Incantatem," but the clothes stayed the same.

Then the bully shrugged, and, still facing in the direction of Lavender instead of the dangling fourth-year boy, drew back his fist -

"Lagann!" yelled five voices, and five green spirals blasted from five wands aimed through five holes in the false wall, and an instant later Hermione's voice shouted "Stupefy!"

Five green spirals shattered ineffectually on blue haze, and Hermione's red bolt bounced off the haze and struck the fourth-year boy, who jerked and then was still.

And the seventh-year bully turned around, smiling grimly, as the first-year girls screamed and charged.