Draco Malfoy and the Practice of Rationality

A continuation of Harry Potter and the Methods of Rationality, focusing on Draco in his second year. I try to not deviate from HPMOR, but I may make mistakes and there are some plot points open to interpretation. More political than HPMOR, but still some cognitive psychology ala Harry's Lessons. And not nearly as good, so lower your expectations.


Asymmetric Warfare, Part 2

“People promise according to their hopes, but perform according to theirfears.” - Lucius Malfoy

They came just after midnight.

By tradition - almost as old as Hogwarts itself - Slytherin plots inside thedorms were limited to maneuvering. No fights, no thefts, no duels (savingSlytherin Duels) took place in the Dungeons itself. A Slytherin coul


Asymmetric Warfare

“When you strike you have either won decisively or planned poorly.” - LuciusMalfoy


Draco stalked the non-Forbidden Forest, feet shuffling along the ground. Thestarting gong had echoed off ten or fifteen minutes ago, so the enemy could benearby. Walking normally meant stepping on leaves and that meant noise,quietus or no quietus. Pushi


The Halo Effect

“Do not get greedy. Have partners share your gains. This provides alliesagainst losses.” - Lucius Malfoy

The Bayesian Conspiracy met after dinner at least once a week, tonight’ssession had just passed the two hour mark.

“All of these ideas,” said Neville, “they let us check a solution. But theydon’t help us come up with the answer.” Harry just raised


Bold Thinking, Part 3

‘You will rarely be caught in a lie your victim wants to believe. He wouldrather make the lie come true than expose you.” - Lucius Malfoy

“What I’m trying to get at,” Harry Potter said to the gathered BayesianConspiracy, located in the potions classroom near Slytherin, “is that thefastest course of action is to make the boldest prediction possible,



“Trust but verify. Distrust and verify. Remain uncertain and verify. Alwaysverify.” - Lucius Malfoy

Imagine you are a future Voldemort, aged twelve.

You are surrounded by lesser wizards, wizards you will mock, torture, and killwith impunity when you are older. They are, all of them, beneath you. You longfor that day to come, when you cast off your mask of civilit


Bold Thinking, Part 2

“Vagueness is a powerful tool, especially vagueness of motive.” - LuciusMalfoy

“Well done Draco,” said Professor Lockhart, as the first years rushed out ofthe lecture hall, chatting excitedly about their upcoming first battle,scheduled for Sunday. “As always, I suppose I should say.”

“I don’t know,” said Draco. “Nobody is staying after class to as


Bold Thinking, Part 1

“Foolish people work hard to appear happy. Work hard to be happy.” - LuciusMalfoy

The howler arrived early, well before breakfast. It didn’t arrive in the GreatHall, of course. Draco had heard Tanaxu’s arrival and groggily opened his eyesin time to see the letter, growing red and about to burst. Draco managed tograb the letter and dive i


Defence and Offence, Part 3

“A fact your enemy does not know is a handful of Galleons. A fact your enemyknows incorrectly is a treasure beyond price.”

- Lucius Malfoy

Draco got up gingerly from the table, dinner unfinished.

“Aren’t you hungry?” asked Gregory. When Draco shook his head, Gregory grabbedthe roll off of Draco’s plate. At least this year Draco wou


Defence and Offence, Part 2

_Asking someone for a favor can form a powerful bond. _

- Lucius Malfoy

Draco slept through lunch and the first half of History of Magic. Cuttingclass was a non-problem, students routinely answered roll call for each other.As long as you didn’t say ‘present’ twice in a row, Professor Binns nevernoticed. Given his full load Draco had


Defence and Offence

For problems: Attack the urgent, consider the important, ignore the rest.

- Lucius Malfoy, as told to Draco Malfoy (Age 9)

Just before sunrise Draco listened to Hogwarts come alive.

(Hogwarts is not alive.)

Thousands of wizards and witches scattered around the world - but mostly inthe UK - love Hogwarts dearly. They succumbed easily, oft


Known Unknowns

Harry knocked on the door. Gregory cracked it open, glanced at him, thenopened the door just wide enough for Harry to slip through.

The room, off the hallway between the entrance to Slytherin House and thecommons, felt spacious. Not as large as Harry’s trunk, but almost as large asthe room his trunk sat in last year, with the rest of the Ravenclaw first yea


Unknown Unknowns, Part 2

“So tell me, Malfoy, do you fancy Granger?” Ethan had asked.

The word No s_tuck in Draco’s throat. Draco heard boys sniggering. The girlsmade no sound and he didn’t know which bothered him more. Harry Potter loungedagainst the back wall, expression no longer unreadable. _He’s smirking, damnhim. Draco tried saying ‘No’ again, just to check.



Unknown Unknowns

They’d barely reached the common area when Ethan Jugson snarled “Why’d you goand do that, Malfoy?”

Professor Slughorn had escorted them himself, chattering merrily aboutstudents’ parents, aunts, and uncles. But when they arrived at the solid oakendoor that formed the entrance to the Dungeons he’d said his goodnight andtottered off, leaving the students t


Efficient Sorting Algorithms

Draco sat comfortably at the Slytherin table staring up into the dusk sky.Clouds drifted lazily from the North and birds, starlings mostly, dartedaround. Draco watched the flock expand and contract, thoughts drifting throughconversations, weighing potential allies and enemies. Vincent and Gregory’sposition took up some thoughts, as did recent


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