Harry Potter and the Methods of Rationality

"Then what does it mean to have the power to vanquish someone?"

Rianne considered the puzzle. (Wishing, not for the first time in her life, that she had chosen Ravenclaw and to perdition with her parents' disapproval; but the Sorting Hat had never offered her Gryffindor.) "Well..." Rianne said. She was having trouble putting her thoughts into words. "It means you've got the power, but you don't have to do it. It means you could do it if you tried -"

"Choice," the Potions Master said in the same faraway voice, as though he wasn't really talking to her at all. "There will be a choice. That is what the riddle seems to imply. And that choice is not a foregone conclusion to the chooser, for the riddle does not say, will vanquish, but rather the power to vanquish. How would a grown man mark a baby as his equal?"

"What?" said Rianne. She didn't understand that at all.

"Marking a baby is simple. Any strong Dark curse would produce a lasting scar. But such may be done to any child. What mark would signify that a baby was your equal?"

She answered with the first thought that came to mind. "If you signed a betrothal contract, that would mean you'd be equals with them someday, when they grew up and you got married."

"That..." said Snape. "That's probably not it, Miss Felthorne, but thank you for trying." The long delicate fingers, honed by stirring potions to unimaginably fine tolerances, reached up and rubbed at the temples of the man's forehead. "It is enough to drive me to madness, so much hinging on such fragile words. Power he knows not... it must be more than some unknown spell. Not something he could acquire simply by practice and study. Some innate talent? No one can learn to be a Metamorphmagus... and yet that hardly seems like a power he knows not. Nor can I see how either could destroy all but a remnant of the other; I can see it in one direction, but not the reverse..." The Potions Master sighed. "And none of this means anything to you, does it, Miss Felthorne? The words are nothing. The words are shadows. It is her intonation which carries the meaning and that is something I've never been able to..."

The Potions Master trailed off, while Rianne stared at him.

"A prophecy?" Rianne said in a high squeak. "You heard a prophecy?" She'd taken Divination for a couple of months before dropping it in disgust, and she knew that much about how it worked.

"I will try one last thing," said Snape. "Something I have not tried before. Miss Felthorne, listen to the sound of my voice, the way I say it, not the words themselves, and tell me what you think it means. Can you do that? Good," said Snape, as she nodded obediently, though she wasn't sure at all what she was supposed to do.

And Severus Snape drew a breath, and intoned, "FOR THOSE TWO DIFFERENT SPELLETS CANNOT EXIST IN THE SAME VULD."

It sent shivers down her spine, all the worse for knowing the hollow words had been spoken in imitation of a true prophecy. Unnerved, she blurted out the first thing which came to mind, which might have been influenced by her present company. "Those two different ingredients cannot exist in the same cauldron?"

"But why not, Miss Felthorne? What is the meaning of a statement like that? What are we really being told?"

"Ah..." she hazarded. "If the two ingredients mix, they'll catch fire and burn the cauldron?"

Snape's face did not change expression in the slightest.

"Perhaps," Snape finally said, after they'd sat on the sofa in awful silence for what seemed like minutes. "It would explain the word must. Thank you, Miss Felthorne. Once again you have been most helpful."

"I -" she said, "I was glad to -" and the words stuck in her throat. The Potions Master had thanked her with a tone of finality, and she knew that the time of the Rianne Felthorne who remembered these moments was drawing to an end. "I wish I didn't have to forget this, Professor Snape!"

"I wish," Severus Snape said in a whisper so low she could hardly hear it, "that everything had been different..."

The Potions Master stood up from the sofa, the weight of his presence vanishing from beside her. He turned and drew his wand from his robes, pointing it at her.

"Wait -" she said. "Before that -"

Somehow it was unbelievably hard to take the first step from fantasy to reality, from imagining to doing. Even if it was only one step and would never go any further. The gap stretched like the distance between two mountains.

The Sorting Hat had never offered her Gryffindor...

...was it fair that thus a woman's life be judged?