Harry stood, panting, in the midst of a brief wasted circle amid the forest, more destruction than a first-year should have been able to reach, by himself. The Severing Charm wouldn't bring down a tree, so he'd started partially Transfiguring cross-sections through the wood. It hadn't let out what was inside him, bringing down a small circle of trees hadn't made him feel any better, all the emotions were still there but while he was destroying trees he at least wasn't thinking about how the feelings couldn't be let out.

After Harry had run out of available magic he'd started tearing off branches with his bare hands and snapping them. His hands were bleeding, though nothing that Madam Pomfrey couldn't fix in the morning. Only Dark magic left permanent scars on wizards.

There came a sound of something moving in the woods, like the hoofbeats of a horse, and Harry whirled, his wand rising once more; some part of his magic had returned while he was working with his hands. It occurred to him for the first time that he was out in the Forbidden Forest alone, and making noise.

What emerged into the moonlight was not the unicorn Harry had expected, but a creature with a lower body like that of a horse, gleaming white-brown beneath the moonlight, and the bare upper chest of a male human with long white hair. The moonlight caught the centaur's face, and Harry saw that the eyes were almost as blue as Dumbledore's, halfway to sapphire.

In one hand the centaur held a long wooden spear, with an overlarge metal blade whose edge did not gleam beneath the moonlight; a gleaming edge, Harry had once read, was the sign of a dull blade.

"So," the centaur said. His voice was low, powerful and male. "Here you are, surrounded by destruction. I can smell the unicorn's blood in the air, the blood of something innocent, slain to save oneself."

A jolt of sudden fear brought Harry into the now, and he said quickly, "It's not what it looks like."

"I know. The stars themselves proclaim your innocence, ironically enough." The centaur took a step toward Harry within the small clearing, still holding his spear upright. "A strange word, innocence. It means lack of knowledge, like the innocence of a child, and also means lack of guilt. Only those entirely ignorant can lack all responsibility for the consequences of their actions. He knows not what he does, and therefore can be without harmful intent; so says that word." The deep voice did not echo in the woods.

Harry's eyes flickered to the spear-tip, and he realized that he should have grabbed his Time-Turner the moment he saw the centaur. Now, if Harry tried to reach beneath his robes, the spear could strike him before then, if the centaur was fast enough. "I read once," Harry said, his voice a bit unsteady as he tried to match deep-sounding words to deep-sounding words, "that it's wrong to think of little children as innocent, because not knowing isn't the same as not choosing. That children do little harms to each other with schoolyard fights, because they don't have the power to do great harm. And some adults do great harm. But the adults who don't, aren't they more innocent than children, not less?"

"The wisdom of wizards," the centaur said.

"Muggle wisdom, actually."

"Of the magicless I know little. Mars has been dim of late, but it grows brighter." The centaur took another step forwards, bringing him almost within striking distance of Harry.

Harry didn't dare look up to the sky. "That means Mars is coming closer to the Earth, as both planets go around the Sun. Mars is reflecting the same amount of sunlight as always, it's just getting nearer to us. What do you mean, the stars proclaim my innocence?"

"The night sky speaks to centaurs. It is how we know what we know. Or do they not even tell wizards that much, these days?" A look of contempt crossed the centaur's face.

"I... tried to look up centaurs, when I was checking out Divination. Most of the authors just ridiculed centaur Divination without explaining why, wizards don't understand argumentative norms, to them ridiculing an idea or a person feels like casting that idea down just as much as bringing evidence against it... I thought the part about centaurs using astrology was just more ridicule..."

"Why?" the centaur intoned. His head cocked curiously.

"Because the course of the planets is predictable for thousands of years in advance. If I talked to the right Muggles, I could show you a diagram of exactly what the planets will look like from this spot ten years later. Would you be able to make predictions from that?"

The centaur shook his head. "From a diagram? No. The light of the planets, the comets, the subtle shifts in the stars themselves, those I would not see."

"Cometary orbits are also set thousands of years in advance so they shouldn't correlate much to current events. And the light of the stars takes years to travel from the stars to Earth, and the stars don't move much at all, not visibly. So the obvious hypothesis is that centaurs have a native magical talent for Divination which you just, well, project onto the night sky."

"Perhaps," the centaur said thoughtfully. His head lowered. "The others would strike you for saying such a thing, but I have ever sought to know what I do not know. Why the night sky can foretell the future - that I surely do not know. It is hard enough to grasp the skill itself. All I can say, son of Lily, is that even if what you are saying is true, it does not seem useful."

Harry allowed himself to relax a little; being addressed as 'son of Lily' implied that the centaur thought of him as more than a random intruder in the forest. Besides, attacking a Hogwarts student would probably bring some kind of huge reprisal upon the non-wizard centaur tribe in the forests, and the centaur probably knew that... "What Muggles have learned is that there is a power in the truth, in all the pieces of the truth which interact with each other, which you can only find by discovering as many truths as possible. To do that you can't defend false beliefs in any way, not even by saying the false belief is useful. It might not seem to matter whether your predictions are really based on the stars or if it's an innate talent being projected. But if you wanted to really understand Divination, or for that matter the stars, the real truth about centaur predictions would be a fact that matters to other truths."

Slowly the centaur nodded. "So the wandless have become wiser than the wizards. What a joke! Tell me, son of Lily, do the Muggles in their wisdom say that soon the skies will be empty?"

"Empty?" Harry said. "Er... no?"

"The other centaurs in this forest have stayed from your presence, for we are sworn not to set ourselves against the heavens' course. Because, in becoming entangled in your fate, we might become less innocent in what is to come. I alone have dared approach you."

"I... don't understand."

"No. You are innocent, as the stars say. And to slay something innocent to save oneself, that is a terrible deed. One would live only a cursed life, a half-life, from that day. For any centaur would surely be cast out, if he slew a foal."

The spear made a lightning motion, too fast for Harry's eyes to follow, and smashed his wand out of his hand.

Another powerful blow smashed into Harry's solar plexus, and he went gasping and retching to the forest floor.

Harry's hand reached up toward his robes, for his Time-Turner, and the spear-butt knocked his hand away, almost hard enough to break fingers, he reached with his other hand and that was knocked away too -

"I am sorry, Harry Potter," the centaur said, and then looked up with widened eyes. The spear spun about and came up, intercepting a red spellbolt. Then the centaur dropped the spear and leaped away desperately, a green flash of light went past him and another green flash of light followed in its wake, then a third green flash hit the centaur straight-on.

The centaur fell and did not move again.

It took a long time for Harry to catch his breath, to stagger to his feet, to pick up his wand, to croak, "What?"

By that time the sense of doom, of power almost tangible in the air, had approached once more.

"P-Professor Quirrell? What are you doing here?"

"Well," the man in the black cloak said thoughtfully, "you needed to fly into a rage and have a loud tantrum in the Forbidden Forest in the middle of the night, and I needed to go just outside your ability to detect me and keep watch. One does not leave a student alone in the Forbidden Forest. That should be obvious in retrospect."

Harry stared at the fallen centaur.

The horse-form wasn't breathing.

"You - you killed him, that was Avada Kedavra -"

"I do not always understand how other people imagine morality to work, Mr. Potter. But even I know that on conventional morality, it is acceptable to kill nonhuman creatures which are about to slay a wizard child. Perhaps you do not care about the nonhuman part, but he was about to kill you. He was hardly innocent -"

The Defense Professor stopped, looking at Harry, who had raised one trembling hand to his mouth.

"Well," the Defense Professor said then, "I have made my point, and you may think on it. Centaur spears can block many spells, but no one tries to block if they see that the spell is a certain shade of green. For this purpose it is useful to know some green stunning hexes. Really, Mr. Potter, you should understand by now how I operate."

The Defense Professor came nearer the centaur's body, and Harry took an involuntary step back, then another, at the terrible rising sense of STOP, DON'T -

The Defense Professor kneeled and pressed his wand to the centaur's head.

The wand stayed there for a time.

And the centaur rose, eyes blank, breathing once more.

"Remember nothing of this time," the Defense Professor commanded. "Wander away and forget everything about this night."

The centaur walked away, the four horse-legs moving in strange synchrony.

"Happy now?" the Defense Professor said, sounding rather sardonic about it.

Harry's brain still felt broken. "He was trying to kill me."

"Oh, for Merlin's sake - yes, he was trying to kill you. Get used to it. Only boring people never have that experience."

Harry's voice emerged, hoarse. "Why - why did he want to -"

"Any number of reasons. I would be lying if I said I'd never considered killing you myself."

Harry stared at where the centaur had wandered into the trees.

His brain still felt half-broken, like an engine misfiring, but Harry did not see how this could possibly be a good sign.

The news of Draco Malfoy nearly being eaten by a horror had been sufficient to summon back Dumbledore from wherever he'd gone, to wake Lord Malfoy and the Lady Greengrass's handsome husband, to bring forth Amelia Bones. The supposed presence of the horror had provoked skepticism even from Dumbledore, and the possibility of False Memory Charms had been raised. Harry had said (after some internal debate about the consequences of people believing a demon was on the loose) that he didn't actually remember making the same effort he'd put forth to frighten the Dementor, the dark thing had just left; which was what you would expect someone to create as a False Memory, if they hadn't actually known how Harry had done it. The names of Bellatrix Black, Severus Snape, and Quirinus Quirrell had been mentioned in connection with wizards strong enough to subdue everyone present and cast False Memory Charms, and Harry had known that Lucius was thinking of Dumbledore. There had been Aurors testifying, and discussions going in circles, and glares of accusation, and cutting remarks at 2AM in the morning. There had been motions, and votes, and consequences.

"Do you believe," Headmaster Dumbledore said quietly to Harry, when all of it was done, and the two of them alone, "that the Hogwarts you have wrought is an improvement?"

Harry sat with his elbows on his knees, his face resting on his palms, in the conference room from which all the others had now departed. Professor McGonagall, who did not use a Time-Turner as routinely as the two of them, had departed swiftly for her bed.

"Yes," Harry answered after too long a hesitation. "From my perspective, Headmaster, things in Hogwarts are finally, finally normal. This is how things should be, when four children get sent into the Forbidden Forest at night. There should be a huge fuss, constables showing up, and the responsible party getting sacked."

"You believe it is good," Dumbledore said quietly, "that the man who you call responsible was, as you put it, sacked."

"Yes, in fact, I do."

"Argus Filch has served this institution for decades."

"And when given Veritaserum," Harry said tiredly, "Argus Filch revealed that he had sent an eleven-year-old boy into the Forbidden Forest, hoping something awful would happen to him, because he thought the boy's father had been responsible for the death of his cat. The three other students in Draco's company don't seem to have fazed him. I would have argued for jail time, but your concept of jail in this country is Azkaban. I'll also note that Filch was remarkably unpleasant to the children in Hogwarts and I expect the school's hedonic index to be improved by his departure, not that it matters to you, I suppose."

The Headmaster's eyes were impenetrable behind the half-moon glasses. "Argus Filch is a Squib. His work at Hogwarts is all he has. Had, rather."

"The purpose of a school is not to provide work for its employees. I know you probably spent more time around Filch than around any individual student, but that shouldn't make Filch's inner experiences loom larger in your thoughts. Students have inner lives too."

"You don't care at all, do you Harry?" Dumbledore's voice was quiet. "About those you hurt."

"I care about the innocent," Harry said. "Like Mr. Hagrid, who you'll note I argued should not be considered malicious, just oblivious. I was fine with Mr. Hagrid working here so long as he didn't take anyone into the Forbidden Forest again."

"I had thought that with Rubeus vindicated, he might teach Care of Magical Creatures after Silvanus departs the position. But much of that teaching is done in the Forbidden Forest. So that too shall not be, in the wake of your passage."

Harry said slowly, "But - you told us that Mr. Hagrid has a blind spot when it comes to magical creatures threatening wizards. That Mr. Hagrid had a cognitive deficit and couldn't really imagine Draco and Tracey getting hurt, which was why Mr. Hagrid didn't see anything wrong with leaving them alone in the Forbidden Forest at night. Was that not true?"

"It is true."

"Then wouldn't Mr. Hagrid be the worst possible teacher for Magical Creatures?"

The old wizard gazed down at Harry through the half-moon glasses. His voice was thick when he spoke. "Mr. Malfoy himself saw nothing awry. It was not so implausible a trick which Argus played, Harry Potter. And Rubeus might have grown into his position. It would have been - all Rubeus wished, his one greatest desire -"

"Your mistake," Harry said, looking down at his knees, feeling at least ten percent as exhausted as he'd ever been, "is a cognitive bias we would call, in the trade, scope insensitivity. Failure to multiply. You're thinking about how happy Mr. Hagrid would be when he heard the news. Consider the next ten years and a thousand students taking Magical Creatures and ten percent of them being scalded by Ashwinders. No one student would be hurt as much as Mr. Hagrid would be happy, but there'd be a hundred students being hurt and only one happy teacher."

"Perhaps," the old wizard said. "And your own error, Harry, is that you do not feel the pain of those you hurt, once you have done your multiplication."

"Maybe." Harry went on staring at his knees. "Or maybe it's worse than that. Headmaster, what does it mean if a centaur doesn't like me?" What does it mean when a member of a race of magical creatures known for Divination gives you a lecture on people who are ignorant of consequences, apologizes, and then tries to stab you with a spear?

"A centaur?" the Headmaster said. "When did you - ah, the Time-Turner. You are the reason why I could not travel back to before the event, on pain of paradox."

"Am I? I guess I am." Harry shook his head distantly. "Sorry."

"With very few exceptions," Dumbledore said, "centaurs do not like wizards, at all."

"This was a bit more specific than that."

"What did the centaur say to you?"

Harry didn't reply.

"Ah." The Headmaster hesitated. "Centaurs have been wrong many times, and if there is anyone in the world who could confuse the stars themselves, it is you."

Harry looked up, and saw the blue eyes once more gentle behind the half-circle glasses.

"Do not fret too much about it," said Albus Dumbledore.