Harry Potter and the Methods of Rationality

No doubt you are already thinking of all manner of wonderful pranks, as your father committed in his day. If his full misdeeds were known, every woman in Gryffindor would gather to desecrate his grave. I shall not try to stop history from repeating, but be MOST careful not to reveal yourself. If Dumbledore saw a chance to possess one of the Deathly Hallows, he would never let it escape his grasp until the day he died.

A Very Merry Christmas to you.

The note was unsigned.

"Hold on," Harry said, pulling up short as the other boys were about to leave the Ravenclaw dorm. "Sorry, there's something else I've got to do with my trunk. I'll be along to breakfast in a couple of minutes."

Terry Boot scowled at Harry. "You'd better not be planning to go through any of our things."

Harry held up one hand. "I swear that I intend to do nothing of the sort to any of your things, that I only intend to access objects that I myself own, that I have no pranking or otherwise questionable intentions towards any of you, and that I do not anticipate those intentions changing before I get to breakfast in the Great Hall."

Terry frowned. "Wait, is that -"

"Don't worry," said Penelope Clearwater, who was there to guide them. "There were no loopholes. Well-worded, Potter, you should be a lawyer."

Harry Potter blinked at that. Ah, yes, Ravenclaw prefect. "Thank you," he said. "I think."

"When you try to find the Great Hall, you will get lost." Penelope stated this in the tones of a flat, unarguable fact. "As soon as you do, ask a portrait how to get to the first floor. Ask another portrait the instant you suspect you might be lost again. Especially if it seems like you're going up higher and higher. If you are higher than the whole castle ought to be, stop and wait for search parties. Otherwise we shall see you again four months later and you will be five months older and dressed in a loincloth and covered in snow and that's if you stay inside the castle."

"Understood," said Harry, swallowing hard. "Um, shouldn't you tell students all that sort of stuff right away?"

Penelope sighed. "What, all of it? That would take weeks. You'll pick it up as you go along." She turned to go, followed by the other students. "If I don't see you at breakfast in thirty minutes, Potter, I'll start the search."

Once everyone was gone, Harry attached the note to his bed - he'd already written it and all the other notes, working in his cavern level before everyone else woke up. Then he carefully reached inside the Quietus field and pulled the Cloak of Invisibility off Harry-1's still-sleeping form.

And just for the sake of mischief, Harry put the Cloak into Harry-1's pouch, knowing it would thereby already be in his own.

"I can see that the message is passed on to Cornelion Flubberwalt," said the painting of a man with aristocratic airs and, in fact, a perfectly normal nose. "But might I ask where it came from originally?"

Harry shrugged with artful helplessness. "I was told that it was spoken by a hollow voice that belled forth from a gap within the air itself, a gap that opened upon a fiery abyss."

"Hey!" Hermione said in tones of indignation from her place on the other side of the breakfast table. "That's everyone's dessert! You can't just take one whole pie and put it in your pouch!"

"I'm not taking one pie, I'm taking two. Sorry everyone, gotta run now!" Harry ignored the cries of outrage and left the Great Hall. He needed to arrive at Herbology class a little early.

Professor Sprout eyed him sharply. "And how do you know what the Slytherins are planning?"

"I can't name my source," Harry said. "In fact I have to ask you to pretend that this conversation never happened. Just act like you happened across them naturally while you were on an errand, or something. I'll run on ahead as soon as Herbology gets out. I think I can distract the Slytherins until you get there. I'm not easy to scare or bully, and I don't think they'll dare to seriously hurt the Boy-Who-Lived. Though... I'm not asking you to run in the hallways, but I would appreciate it if you didn't dawdle along the way."

Professor Sprout looked at him for a long moment, then her expression softened. "Please be careful with yourself, Harry Potter. And... thank you."

"Just be sure not to be late," Harry said. "And remember, when you get there, you weren't expecting to see me and this conversation never happened."