Harry Potter and the Methods of Rationality

"Really?" Harry said. "But you just told us you'd teach us how to bottle fame. Say, how does that work, exactly? You drink it and turn into a celebrity?"

Three-quarters of the class flinched.

Hermione's hand was dropping slowly back down. Well, that wasn't surprising. She might be his rival, but she wasn't the sort of girl who would play along after it became clear that the professor was deliberately trying to humiliate him.

Harry was trying hard to keep control of his temper. The first rejoinder that had crossed his mind was 'Abracadabra'.

"Let's try again," said Severus. "Potter, where would you look if I told you to find me a bezoar?"

"That's not in the textbook either," Harry said, "but in one Muggle book I read that a trichinobezoar is a mass of solidified hair found in a human stomach, and Muggles used to believe it would cure any poison -"

"Wrong," Severus said. "A bezoar is found in the stomach of a goat, it is not made of hair, and it will cure most poisons but not all."

"I didn't say it would, I said that was what I read in one Muggle book -"

"No one here is interested in your pathetic Muggle books. Final try. What is the difference, Potter, between monksblood and wolfsbane?"

That did it.

"You know," Harry said icily, "in one of my quite fascinating Muggle books, they describe a study in which people managed to make themselves look very smart by asking questions about random facts that only they knew. Apparently the onlookers only noticed that the askers knew and the answerers didn't, and failed to adjust for the unfairness of the underlying game. So, Professor, can you tell me how many electrons are in the outermost orbital of a carbon atom?"

Severus's smile widened. "Four," he said. "It is a useless fact which no one should bother writing down, however. And for your information, Potter, asphodel and wormwood make a sleeping potion so powerful it is known as the Draught of Living Death. As for monkshood and wolfsbane, they are the same plant, which also goes by the name of aconite, as you would know if you had read One Thousand Magical Herbs and Fungi. Thought you didn't need to open the book before coming, eh, Potter? All the rest of you should be copying that down so that you will not be as ignorant as him." Severus paused, looking quite pleased with himself. "And that will be... five points? No, let us make it an even ten points from Ravenclaw for backchat."

Hermione gasped, along with a number of others.

"Professor Severus Snape," Harry bit out. "I know of nothing which I have done to earn your enmity. If there is some problem you have with me which I do not know about, I suggest we -"

"Shut up, Potter. Ten more points from Ravenclaw. The rest of you, open your books to page 3."

There was only a slight, only a very faint burning sensation in the back of Harry's throat, and no moisture at all in his eyes. If crying was not an effective strategy for destroying this Potions professor then there was no point in crying.

Slowly, Harry sat up very straight. All his blood seemed to have been drained away and replaced with liquid nitrogen. He knew he'd been trying to keep his temper but he couldn't seem to remember why.

"Harry," whispered Hermione frantically from two desks over, "stop, please, it's all right, we won't count it -"

"Talking in class, Granger? Three -"

"So," said a voice colder than zero Kelvin, "how does one go about filing a formal complaint against an abusive professor? Does one talk to the Deputy Headmistress, write a letter to the Board of Governors... would you care to explain how it works?"

The class was utterly frozen.

"Detention for one month, Potter," Severus said, smiling even more broadly.

"I decline to recognize your authority as a teacher and I will not serve any detention you give."

People stopped breathing.

Severus's smile vanished. "Then you will be -" his voice stopped short.

"Expelled, were you about to say?" Harry, on the other hand, was now smiling thinly. "But then you seemed to doubt your ability to carry out the threat, or fear the consequences if you did. I, on the other hand, neither doubt nor fear the prospect of finding a school with less abusive professors. Or perhaps I should hire private tutors, as is my accustomed practice, and be taught at my full learning speed. I have enough money in my vault. Something about bounties on a Dark Lord I defeated. But there are teachers at Hogwarts who I rather like, so I think it will be easier if I find some way to get rid of you instead."

"Get rid of me?" Severus said, now also smiling thinly. "What an amusing conceit. How do you suppose you will do that, Potter?"

"I understand there have been a number of complaints about you from students and their parents," a guess but a safe one, "which leaves only the question of why you're not already gone. Is Hogwarts too financially strapped to afford a real Potions professor? I could chip in, if so. I'm sure they could find a better class of teacher if they offered double your current salary."

Two poles of ice radiated freezing winter across the classroom.

"You will find," Severus said softly, "that the Board of Governers is not the slightest bit sympathetic to your offer."

"Lucius..." Harry said. "That's why you're still here. Perhaps I should chat with Lucius about that. I believe he desires to meet with me. I wonder if I have anything he wants?"

Hermione frantically shook her head. Harry noticed out of the corner of his eye, but his attention was all on Severus.