Harry Potter and the Methods of Rationality

Evil rich people charged you annual interest rates of at least 20%.

Harry had stood up, turned away, and rested his head against the wall.

Harry had asked if he needed the Headmaster's permission before he could start a bank.

Professor Quirrell had interrupted at this point, saying that it was time for lunch, and swiftly conducted a fuming Harry out of the bronze doors of Gringotts, through Diagon Alley, and to a fine restaurant called Mary's Place, where a room had been reserved for them. The owner had looked shocked at seeing Professor Quirrell accompanied by Harry Potter, but had conducted them to the room without complaint.

And Professor Quirrell had quite deliberately announced that he would pay the bill, seeming to rather enjoy the look on Harry's face.

'No,' said Professor Quirrell to the waitress, 'we will not require menus. I will have the daily special accompanied by a bottle of Chianti, and Mr. Potter will have the Diracawl soup to start, followed by a plate of Roopo balls, and treacle pudding for dessert.'

The waitress, clad in robes that still looked severe and formal while being rather shorter than usual, bowed respectfully and departed, shutting the door behind her.

Professor Quirrell waved a hand in the direction of the door, and a bolt slid shut. 'Note the bolt on the inside. This room, Mr. Potter, is known as Mary's Room. It happens to be proof against all scrying, and I do mean all; Dumbledore himself could detect nothing of what happens here. Mary's Room is used by two kinds of people. The first sort are engaged in illicit dalliances. And the second sort lead interesting lives.'

'Really,' said Harry.

Professor Quirrell nodded.

Harry's lips were parted in anticipation. 'It would be a waste to just sit here and eat lunch, then, without doing anything special.'

Professor Quirrell grinned, then took out his wand and flicked it in the direction of the door. 'Of course,' he said, 'people who lead interesting lives take precautions more thorough than the dalliers. I have just sealed us in. Nothing will now pass in or out of this room - through the crack under the door, for example. And...'

Professor Quirrell then spoke no fewer than four different Charms, none of which Harry recognized.

'Even that does not really suffice,' said Professor Quirrell. 'If we were doing anything of truly great import, it would be necessary to perform another twenty-three checks besides those. If, say, Rita Skeeter knew or guessed that we would come here, it is possible that she could be in this room wearing the true Cloak of Invisibility. Or she could be an Animagus with a tiny form, perhaps. There are tests to rule out such rare possibilities, but to perform all of them would be arduous. Still, I wonder if I should do them anyway, just so as not to teach you bad habits?' And Professor Quirrell tapped a finger on his cheek, looking abstracted.

'It's fine,' Harry said, 'I understand, and I'll remember.' Though he was a little disappointed that they weren't doing anything of truly great import.

'Very well,' Professor Quirrell said. He leaned back in his chair, smiling broadly. 'You wrought quite well today, Mr. Potter. The basic notion was yours, I'm sure, even if you delegated the execution. I don't think we'll be hearing much more from Rita Skeeter after this. Lucius Malfoy will not be pleased with her failure. If she's smart, she'll flee the country the instant she realizes she's been fooled.'

A sinking sensation began to dawn in Harry's stomach. 'Lucius was behind Rita Skeeter...?'

'Oh, you didn't realize that?' said Professor Quirrell.

Harry hadn't thought about what would happen to Rita Skeeter afterward.

At all.

Not in the slightest.

But she would get fired from her job, of course she would be fired, she might have children going through Hogwarts for all Harry knew, and now it was worse, much worse -

'Is Lucius going to have her killed?' Harry said in a barely audible voice. Somewhere in his head, the Sorting Hat was screaming at him.

Professor Quirrell smiled dryly. 'If you have not dealt with journalists before, take it from me that the world gets a little brighter every time one dies.'

Harry jumped out of his chair with a convulsive movement, he had to find Rita Skeeter and warn her before it was too late -

'Sit down,' Professor Quirrell said sharply. 'No, Lucius won't kill her. But Lucius makes life extremely unpleasant for those who serve him ill. Miss Skeeter will flee and start her life over with a new name. Sit down, Mr. Potter; there is nothing you can do at this point, and you have a lesson to learn.'

Harry sat down, slowly. There was a disappointed, annoyed look on Professor Quirrell's face that was doing more to stop him than the words.

'There are times,' Professor Quirrell said, his voice cutting, 'when I worry that your brilliant Slytherin mind is simply wasted on you. Repeat after me. Rita Skeeter was a vile, disgusting woman.'

'Rita Skeeter was a vile, disgusting woman,' Harry said. He wasn't comfortable saying it, but there didn't seem to be any other possible actions, none at all.

'Rita Skeeter tried to destroy my reputation, but I executed an ingenious plan and destroyed her reputation first.'

'Rita Skeeter challenged me. She lost the game, and I won.'

'Rita Skeeter was an obstacle to my future plans. I had no choice but to deal with her if I wanted those plans to