Up to twenty seconds of exposure at five paces was certainly safe, even for an eleven-year-old wizard with weak resistance and a still-maturing brain. There was a lot of variance in how hard the Dementor's power hit people, which was another thing not quite understood; but twenty seconds was definitely safe.
Forty seconds of Dementor exposure at five paces might possibly have been enough to cause permanent damage, though only to the most sensitive subjects.
It was harsh training even by the standards of Hogwarts, where the way you learned to fly on a hippogriff was by being tossed on one and told to get going. Harry was no fan of overprotectiveness, and if you looked at the difference in maturity between a fourth-year in Hogwarts and a fourteen-year-old Muggle, it was clear that Muggles were smothering their children... but even Harry had started to wonder if this was pushing it. Not every hurt could be healed afterward.
But if you couldn't cast the spell under those conditions, it meant you couldn't rely on using the Patronus Charm to defend yourself; overconfidence was even more dangerous to wizards than to Muggles. Dementors could drain your magic and your physical vitality, not just your happy thoughts, which meant you might not be able to Apparate away if you waited too long, or if you didn't recognize the approaching fear until the Dementor was within range for its attack. (During his reading, Harry had discovered with considerable horror that some books claimed the Dementor's Kiss would eat your soul and that this was the reason for the permanent mindless coma into which it put the victims. And that wizards who believed this had deliberately used the Dementor's Kiss to execute criminals. It was a certainty that some called criminals were innocent, and even if they weren't, destroying their souls? If Harry had believed in souls, he would have... drawn a blank, he just couldn't think of an appropriate response to that.)
The Headmaster was taking security seriously, and so were the three Aurors standing guard. Their leader was an Asianish-looking man, solemn without being grim, Auror Komodo, whose wand never left his hand. His Patronus, an orangutan of solid moonlight, paced back and forth between the Dementor and the first-years awaiting their turn; beside the orangutan moved the bright white panther of Auror Butnaru, a man with a piercing gaze, long black hair in a ponytail, and a long braided goatee. Those two Aurors, and their two Patronuses, were all watching the Dementor. On the opposite side of the students was the resting Auror Goryanof, tall and thin and pale and unshaven, sitting back on a chair he'd conjured without word or wand, and maintaining an absentminded pokerface as he scanned the entire scene. Professor Quirrell had shown up not long after the first-years began their attempts, and his eyes never strayed far from Harry. The tiny Professor Flitwick, who had been a champion duellist, was fiddling absently with his wand; and his eyes, peering out from within the huge puffy beard that served as his face, stayed focused on Professor Quirrell.
And it must have been Harry's imagination, but Professor Quirrell seemed to wince slightly each time the Headmaster's Patronus winked out to test the next student. Maybe Professor Quirrell was imagining the same placebo effect as Harry, that backwash of emptiness caressing at his mind.
"Anthony Goldstein," called the voice of the Headmaster.
Harry quietly walked toward Seamus, even as Anthony began to approach the shining silver phoenix, and... whatever it was beneath the tattered cloak.
"What did you see?" Harry asked Seamus in a low voice.
A lot of students hadn't answered Harry, when he'd tried to gather the data; but Seamus was Finnigan of Chaos, one of Harry's lieutenants. Maybe that wasn't fair, but...
"Dead," said Seamus in a whisper, "grayish and slimy... dead and left in water for a while... "
Harry nodded. "That's what a lot of people see," Harry said. He projected confidence, even though it was fake, because Seamus needed it. "Go eat some chocolate, you'll feel better."
Seamus nodded and stumbled off toward the table of healing sweets.
"Expecto Patronum!" cried a young boy's voice.
Then there were gasps of shock, even from the Aurors.
Harry spun around to look -
There was a brilliant silver bird standing between Anthony Goldstein and the cage. The bird reared its head and let out a cry, and the cry was also silver, as bright and hard and beautiful as metal.
And something in the back of Harry's mind said, if that's a peregrine falcon, I'm going to strangle him in his sleep.
Shut up, Harry said to the thought, do you want us to be a Dark Wizard?
What's the point? You're going to end up as one eventually.
That... wasn't something Harry would usually have thought...
It's a placebo effect, Harry told himself again. The Dementor can't actually get to me through three corporeal Patronuses, I'm just imagining what I think it's like. When I actually face the Dementor, it'll feel completely different, and then I'll know I was just being silly before.
A slight chill went down Harry's spine then, because he had a feeling that yes, it would be completely different, and not in a positive direction.
The blazing silver phoenix sprang back into existence from the Headmaster's wand, the lesser bird vanished; and Anthony Goldstein began to walk back.
The Headmaster was coming with Anthony instead of calling out the next name, the Patronus waiting behind to guard the Dementor.
Harry glanced over to where Hermione was standing, just behind the glowing panther. Hermione's turn would have come next, but had apparently just been delayed.
She looked stressed.
Earlier, she'd politely asked Harry to please stop trying to destress her.
Dumbledore was smiling slightly as he escorted Anthony back toward the others; smiling only slightly, because the Headmaster looked very, very tired.
"Unbelievable," said Dumbledore in a voice that sounded much weaker than his accustomed boom. "A corporeal Patronus, in his first year. And an astounding number of successes among the other young students. Quirinus, I must acknowledge that you have proved your point."
Professor Quirrell inclined his head. "A simple enough guess, I should think. A Dementor attacks through fear, and children are less afraid."
"Less afraid?" said Auror Goryanof from where he was sitting.
"So I said as well," said Dumbledore. "And Professor Quirrell pointed out that adults had more courage, not less to fear; which thought, I confess, had never occurred to me before."
"That was not my precise phrasing," Professor Quirrell said dryly, "but it will do. And the rest of our agreement, Headmaster?"
"As you say," Dumbledore said reluctantly. "I admit I was not expecting to lose that wager, Quirinus, but you have proven your wisdom."
All the students were looking at them, puzzled; except Hermione, who was staring in the direction of the cage and the tall decaying robes; and Harry, who was watching everyone, since he was imagining himself feeling paranoid.
Professor Quirrell said, in tones that did not invite further comments, "I am allowed to teach the Killing Curse to students who wish to learn it. Which will render them considerably safer from Dark Wizards and other pests, and it is foolish to think they will otherwise know no deadly magics." Professor Quirrell paused, his eyes narrowing. "Headmaster, I respectfully observe that you are not looking well. I suggest leaving the remainder of the day's task to Professor Flitwick."
Dumbledore shook his head. "We are almost done for the day, Quirinus. I will last."
Hermione had approached Anthony. "Captain Goldstein," she said, and her voice trembled only a little, "can you give me any advice?"
"Don't be afraid," Anthony said firmly. "Don't think about anything it tries to make you think about. You're not just holding up the wand in front of you as a shield against the fear, you're brandishing your wand to drive the fear away, that's how you make a happy thought into something solid..." Anthony shrugged helplessly. "I mean, I heard all that before, but..."
Other students were starting to congregate around Anthony, with their own questions.
Hermione straightened her shoulders, and followed him.
"What did you see under the cloak?" Harry said to Anthony.
Anthony looked at Harry, surprised, and then answered, "A very tall man who was dead, I mean, sort of dead-shaped and dead-colored... it hurt to see him and I knew that was the Dementor trying to get at me."
Harry looked back out at where Hermione was confronting the cage and the cloak.
Hermione raised her wand into position for the first gestures.
The Headmaster's phoenix winked out of existence.
And Hermione gave a tiny, pathetic shriek, flinched -
- took a step back, Harry could see her wand moving, and then she brandished it and said "Expecto Patronum!"
Nothing happened.
Hermione turned and ran.
"Expecto Patronum!" said the Headmaster's deeper voice, and the silver phoenix blazed back to life.
The young girl stumbled, and kept running, strange sounds beginning to come from her throat.
"Hermione!" Susan yelled it, and Hannah, and Daphne, and Ernie, and they all started to run toward her; even as Harry, who was always thinking one step ahead, spun on his own heel and ran for the table with the chocolate.
Even after Harry had shoved the chocolate into Hermione's mouth and she'd chewed and swallowed, she was still breathing in great gasps and crying, her eyes still seemed unfocused.
She can't have been permanently Demented, Harry thought desperately at the confusion inside him, the horrible fear and deathly fury beginning to twist around each other, she can't have been, she wasn't exposed for even ten seconds let alone forty -
But she could be temporarily Demented, as Harry realized in that moment, there wasn't any rule that you couldn't be temporarily injured by a Dementor in just ten seconds if you were sensitive enough.
Then Hermione's eyes seemed to focus, and dart around, and settle on him.
"Harry," she gasped, and the other students went silent. "Harry, don't. Don't!"
Harry was suddenly afraid to ask what he shouldn't do, was he in her worst memories, or some sleep's nightmare that she was now reliving in waking life?
"Don't go near it!" said Hermione. Her hand reached out, grabbed him by the lapel of his robes. "You mustn't go near it, Harry! It spoke to me, Harry, it knows you, it knows you're here!"
"What -" Harry said, and then cursed himself for asking.
"The Dementor!" said Hermione. Her voice rose to a shriek. "Professor Quirrell wants it to eat you!"
In the sudden hush, Professor Quirrell came forward a few steps; but he didn't approach any closer (Harry was there, after all). "Miss Granger," he said, and his voice was grave, "I think you should have some more chocolate."
"Professor Flitwick, don't let Harry try, send him back!"
The Headmaster had arrived by then, and he and Professor Flitwick were exchanging worried looks.
"I did not hear the Dementor speak," the Headmaster said. "Still..."
"Just ask," said Professor Quirrell, sounding a little weary.
"Did the Dementor say how it would get to Harry?" said the Headmaster.
"All his tastiest parts first," said Hermione, "it would - it would eat -"
Hermione blinked. Some sanity seemed to come back into her eyes.
Then she started crying.
"You were too brave, Hermione Granger," the Headmaster said. His voice was gentle, and clearly audible. "Too much braver than I comprehended. You should have turned and run, not endured and tried to complete your Charm. When you are older and stronger, Miss Granger, I know that you will try again, and I know that you will succeed."
"I'm sorry," Hermione said in gasps, "I'm sorry, I'm sorry, I'm sorry... I'm sorry, Harry, I can't tell you what I saw, I didn't look at it, I didn't dare look at it, I knew it was too horrible to ever be seen..."
It should have been Harry, but he'd hesitated, because his hands were all chocolatey; and then Ernie and Susan were there, helping Hermione from where she'd fallen on the grass, leading her toward the snacks table.
Five bars of chocolate later, Hermione seemed to be all right again, and she went over and apologized to Professor Quirrell; but she was always watching Harry, every time that he glanced in her direction. He'd stepped toward her only once, and stopped when she'd stepped away. Her eyes had silently apologized, and silently pleaded for him to leave her be.
Neville Longbottom had seen something dead and half-dissolved, oozing and running with a face like a squashed sponge.
It was the worst thing anyone had yet described seeing. Neville had been able to produce a small flicker of light from his wand before, but he had, intelligently and with great presence of mind, turned and run away instead of trying to cast his own Patronus Charm.
(The Headmaster had said nothing to the other students, told no one else to be less brave; but Professor Quirrell had calmly observed that if you made the mistake after being warned, that was when ignorance became stupidity.)
"Professor Quirrell?" Harry said in a low voice, having come as close to the Defense Professor as he dared. "What do you see when you -"
"Don't ask." The voice was very flat.
Harry nodded respectfully. "What was your original phrasing to the Headmaster, if I can ask?"
Dryly. "Our worst memories can only grow worse as we grow older."
"Ah," Harry said. "Logical."
Something strange flickered in Professor Quirrell's eyes, then, as he looked at Harry. "Let us hope," Professor Quirrell said, "that you succeed upon this try, Mr. Potter. For if you do, the Headmaster may teach you his trick of using a Patronus to send messages that cannot be forged or intercepted, and the military importance of that is impossible to overstate. It would be a tremendous advantage to the Chaos Legion, and someday, I suspect, this entire country. But if you do not succeed, Mr. Potter... well, I shall understand."
Morag MacDougal had said, in a wavering voice, "Ouch", and Dumbledore had recast his Patronus right away.
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.
Harry Potter and the Methods of Rationality Page 72