Harry Potter and the Methods of Rationality

Parvati Patil had produced a corporeal Patronus in the form of a tiger, larger than Dumbledore's phoenix, though not nearly as bright. There had been a great burst of applause from all the watchers, though not the same shock as when Anthony had done it.

And then it was Harry's turn.

The Headmaster called the name of Harry Potter, and Harry was afraid.

Harry knew, he knew that he was going to fail, and he knew that it was going to hurt.

But he still had to try; because sometimes, in the presence of a Dementor, a wizard went from not a flicker of light to a full corporeal Patronus, and no one understood why.

And because if Harry couldn't defend himself from Dementors, he had to be able to recognize their approach, recognize the feeling of them in his mind, and run before it was too late.

What is my worst memory...?

Harry had expected the Headmaster to give him a worried look, or a hopeful look, or deeply wise advice; but instead Albus Dumbledore only watched him with quiet calm.

He thinks I'm going to fail, but he won't sabotage me by telling me so, thought Harry, if he had true words of encouragement to speak, he would speak them...

The cage came closer. It was already tarnished, but not rusted away to nothing, not yet.

The cloak came closer. It was unraveling and shot through with unpatched holes; it had been new that morning, Auror Goryanof had said.

"Headmaster?" Harry said. "What do you see?"

The Headmaster's voice was also calm. "The Dementors are creatures of fear, and as your fear of the Dementor diminishes, so does the fearsomeness of its form. I see a tall, thin, naked man. He is not decaying. He is only slightly painful to look upon. That is all. What do you see, Harry?"

...Harry couldn't see under the cloak.

Or that wasn't right, it was that his mind was refusing to see what was under the cloak...

No, his mind was trying to see the wrong thing under the cloak, Harry could feel it, his eyes trying to force a mistake. But Harry had done his best to train himself to notice that tiny feeling of confusion, to automatically flinch away from making stuff up; and every time his mind tried to start inventing a lie about what was under the cloak, that reflex was fast enough to shut it down.

Harry looked under the cloak and saw...

An open question. Harry wouldn't let his mind see something false, and so he didn't see anything, like the part of his visual cortex getting that signal was just ceasing to exist. There was a blind spot under the cloak. Harry couldn't know what was under there.

Just that it was far worse than any decaying mummy.

The unseeable horror beneath the cloak was very close, now, but the blazing bird of moonlight, the white phoenix, yet lay between them.

Harry wanted to run away like some of the other students had. Half the ones who'd had no luck with their Patronus Charms just hadn't shown up today in the first place. Of those remaining, half had fled before the Headmaster had even dispelled his own Patronus, and no one had said a word. There'd been a little laughter when Terry had turned and walked back before his own try; and Susan and Hannah, who'd gone before, had yelled at everyone to shut up.

But Harry was the Boy-Who-Lived, and he would lose much respect if he was seen to give up without even trying...

Pride and roles seemed to diminish and fall away, in the presence of whatever lay beneath the cloak.

Why am I still here?

It wasn't the shame of others thinking him cowardly, that kept Harry's feet in place.

It wasn't the hope of repairing his reputation that brought up his wand.

It wasn't the desire to master the Patronus Charm as magic, that moved his fingers into the initial position.

It was something else, something that had to oppose whatever lay beneath the cloak, this was the true darkness and Harry had to find out whether it lay within him, the power to drive it back.

Harry had planned to try one final time to think of his book-shopping spree with his father, but instead, at the last minute, facing the Dementor, a different memory occurred to him, something he hadn't tried before; a thought that wasn't warm and happy in the ordinary way, but felt righter, somehow.

And Harry remembered the stars, remembered them burning terribly bright and unwavering in the Silent Night; he let that image fill him, fill all of him like an Occlumency barrier across his entire mind, became once again the bodiless awareness of the void.

The bright silver shining phoenix vanished.

And the Dementor smashed into his mind like the fist of God.

FEAR / COLD / DARKNESS

There was an instant when the two forces clashed head-on, when the peaceful starlit memory held its own against the fear, even as Harry's fingers began the wand motions, practiced until they had become automatic. They weren't warm and happy, those blazing points of light in perfect blackness; but it was an image the Dementor could not easily pierce. For the silent burning stars were vast and unafraid, and to shine in the cold and darkness was