The moment he spoke the spell, two things happened.
First, the thestral jerked awake, as expected. There was no resonance, no feeling of being torn apart by wild magic, just the feeling of a successfully cast spell. This was also expected, given that the Sense of Doom had seemingly vanished, though Harry still had the sense that he shouldn't have been able to do that.
Second, and entirely unexpected, a letter appeared directly in front of his wand. Harry, who was already on high alert, gave a little start (though thankfully he didn't start loudly), then watched as the letter, addressed To Harry, fell to the ground in front of his invisible hooves. Harry had no time to deal with it, so he simply took a step forward, hoping the Cloak would render it invisible beneath him.
When he looked up again, he saw the thestral glancing around.
(Source: "Pony Creator" flash game)
The slitted, ice-blue eyes took in their surroundings, scanning the meadow until they settled on their owner. For a brief moment, the dark-coated pony froze in place. Then he sighed. After a second of concentration, he spoke the words of a spell Harry recognized as the one that told the user if a Deathly Hallow was present, though it wouldn't give the exact location, nor would it say which Hallow was nearby. Harry had memorized the words to that spell as a precaution, even though he couldn't cast it himself.
There were no outward signs that the spell would yield a positive result, but the thestral's next comment confirmed that it had. "If that is you beneath the Cloak, Mr. P... Mr. Patron, you may as well reveal yourself."
The pegasus who had just been given the alias Mr. Patron did not choose that moment to reveal himself.
The thestral, after a slight pause, switched to Parseltongue. "Plot iss over," hissed whom Harry was now 100% certain to be Tom Riddle. "All iss over. We are losst. Might ass well cooperate for now. Will not harm you."
Harry thought for a moment. Snakes can't lie...
But they can deceive. They can't speak falsehoods, but they can leave out key details, lying by omission. They can lie by saying true things that lead others to form their own false conclusions.
In other words, there might be a loophole. Will not harm you might just be the first part of the sentence, with for now being left out. Or something like that.
So Harry stayed silent, waiting for a more solid commitment to non-aggression.
"I will casst sstunning hex in all directionss if you do not sspeak."
Or that.
Harry whispered "Ventriliquo", pointed his wand at the far end of the clearing, then said in a projected voice, "I'm here." It was weak security at best, but it was better than nothing. "I don't like the name 'Mr. Patron', but it'll do for now. Why did you choose it, Mr. Tome?"
"Short for your signature spell," said the thestral who had just been given the alias 'Mr. Tome.' "Your own designation, however, is worse than a matter of personal preference. It will not do, even for a short while. Choose something else."
"Why?"
"Why indeed, Mr. Plotter."
There was a pause as Harry realized that "Tome" was probably far too close to "Tom" for comfort.
"I see the problem. Sorry, I wasn't thinking about that at all, I just thought it would be better than 'Mr. Book.'"
"Why the focus on literature?"
"Look at your rear."
The thestral frowned. Did as suggested. Made a hmph noise. "I see," he said in a neutral tone. "Mr. Book will do. Do you have one as well?"
"Yes."
"What does it depict?"
"A picture of my signature spell, among other things."
"Then why the distaste for 'Mr. Patron'?"
"It makes me sound like a wealthy aristocrat."
"Very well. Any suggestions?"
"Mr. Silver," the pegasus said after a time. It was still based on his signature spell, just not the name.
"As you wish."
"And you're fine with Mr. Book?"
"I do not mind literature, Mr. Silver," the thestral said sardonically, "nor being named after it. And if there are other creatures like us, the name will not be difficult to explain to them. Will yours? You've yet to show me your appearance."
"My name won't be difficult to explain," Harry answered. Only that. He did not remove his cloak, and continued to maintain the ventriloquism charm.
While he waited for a response, Harry tried to integrate the aliases into his thoughts. Mr. Silver tried to integrate them, rather.
Mr. Book seemed content to keep his eyes closed, brows furrowed in concentration.
Eventually, after it became clear that Mr. Book would not be the next one to speak, and after he was reasonably confident he wouldn't say "Professor Quirrell" by mistake, Mr. Silver spoke.
"You said 'All iss over, we are losst' just now. What does that mean, exactly?"
"I suspect," said Mr. Book, eyes still closed, "that the headmaster did not turn the trap upon himself in the end, and that the True Cloak of Invisibility did not protect me from the Mirror's power." The thestral opened his eyes and began carefully examining his new body. "It would also seem the legends were misinformed. Even I could not have guessed that 'wish-fulfillment' meant..." his voice lowered considerably, "...this. Perhaps one of the Atlanteans allowed their six-year-old daughter to influence the design."
Mr. Silver did not choose that moment to chuckle. "Are you sspeaking truth?" he hissed.
"Am not lying," Mr. Book hissed back. "Iss my besst guesss for why we are here ass we are, but perhapss that iss not the true explanation. Exact reasson doess not matter much, in the end." Then, switching to normal speech, "Though I am annoyed I was not protected by the True Cloak of Invisibility. No magical artifacts can see the Cloak while it is active. I should not have been subject to the Mirror's powers while wearing it. I should not be trapped here with you."
"Actually," said Mr. Silver, a counterexample coming to mind at the phrase 'no magical artifacts can see the cloak', "Mister Moody's magical eye could see straight through the Cloak of Invisibility. I learned that the hard way."
There was a slight pause.
"I wish you had told me that earlier," said a frustrated voice. Then frustration gave way to fury. "Did you keep that fact a ssecret sso that I would be trapped? Did you betray me?"
"No," hissed Mr. Silver. "Jusst thought of it now." Then he frowned. "Though come to think of it, Mr. Moody's eye instantly saw through my cloak. If the Mirror could do the same, you'd think the Mirror's trap would have activated right away, as soon as you had me walk in front of it when I was wearing the cloak. So my own guess is that the Mirror can remember who it sees, even if they put on the Cloak afterwards. But even that's probably not it. I could feel the Time pressure in the air even though I'd been under the Cloak from the start, and you wouldn't think that should happen if I were safe from the effects at the time."
There was a much longer pause. The thestral said nothing in reply, just continued his self-examination.
"You told the headmaster," Mr. Silver said slowly, carefully avoiding the name 'Dumbledore', "that the mirror traps things into a frozen instant. The Timeless Process, I think you called it-"
"The Process of the Timeless," the thestral corrected, tilting a hoof forward, then back. "Though that term was invented by a single scholar. The true name has been lost to time."
"Is that what happened to us?"
Mr. Book nodded, putting down one hoof and turning to the other. "With any luck."
"LUCK?"
"Yes, luck," Mr. Book repeated in a deadpan. He put down both hooves and adopted a lecturing tone. "If we have been trapped outside of Time, then we are no longer at Time's mercy. We exist beyond its influence, thus when we free ourselves, we will be sent back to the moment we were trapped. The hostages you wish to save – and believe it or not, I would also prefer they not die – won't suffer due to this delay. Even if it takes years to achieve freedom on our end, no time at all will pass on that side. If, however, someone frees us from the other side, as the headmaster prophesied you might one day free me, the hostages would be long dead. Not lying," he hissed at the end. "Understand?"
Mr. Silver thought back to the headmaster's conversation with Voldemort.
"You have refused death," said Dumbledore, "and if I destroyed your body, your spirit would only wander back, like a dumb animal that cannot understand it is being sent away. So I am sending you outside Time, to a frozen instant from which neither I nor any other can return you. Perhaps Harry Potter will be able to retrieve you someday, if prophecy speaks true. He may wish to discuss with you just who is at fault for the deaths of his parents. For you it will only be an instant - if you ever return at all. Either way, Tom, I wish you the best of it."
"No," Mr. Silver sighed. "I don't understand. If we're trapped outside of Time, how could Time still keep going on without us? From our perspective, I mean. I got the impression that trapped beings wouldn't be able to do anything at all, and here we are, moving and talking. I get how, from the outside perspective, Time would keep moving forward. But from our perspective, shouldn't Time be frozen?"
"It is, and it isn't," sighed Mr. Book, successfully managing to rub his temples with the tips of his hooves. "Much like how the schoolmaster was both inside the mirror and elsewhere, unfortunately for the two of us. The mirror's powers are double-sided. If a person from outside the mirror releases us fifty years after our initial entrapment, from our perspective no time at all would have passed."
"So," Mr. Silver slowly said as his mind wrapped around the concept, "we wouldn't be having this conversation right now; we'd be back on the other side of the mirror. If someone else had freed us, I mean. We'd be teleported into the distant future, in the presence of some powerful and unknown third party."
Mr. Book nodded. "Since that is not the case, our release will be the result of our own actions, if it is even possible in the first place. Supposing it is possible, we should return to the instant we were trapped. Time is progressing on both sides of the mirror, but only in a mutually exclusive manner. Time progresses here when it is not progressing there. Time progresses there when it is not progressing here. Not lying, but again, theory might be misstaken. Understand now?"
"Yess," Mr. Silver hissed. "It's an optimistic theory, but what if it isn't possible to return? Or if the theory is wrong in some other way?"
The thestral shrugged. "If I am wrong, then there's not much for it. We shall have to adjust to our new circumstances either way. I am rather curious about my new form."
Mr. Silver was curious too. Probably more curious than Mr. Book. He was a Ravenclaw. But there was still one last major problem.
"Your great creation," he hissed. "Your horcruxess." He really didn't want to ask this, but Mr. Book had probably already thought of it, and already tried. Come to think of it, that's probably why the thestral had frozen moments after waking, or why he had closed his eyes in concentration afterwards. "Your connection to your horcruxess hass been ssevered, hass it not?"
There was a long pause during which Mr. Book examined one of his bat-like wings, as if he had not heard the question.
Now that they had a means of communicating truthfully, Mr. Silver knew what it meant if the accusation was not denied in Parseltongue.
"I don't mind exploring this new world," said Mr. Silver after it became clear that Mr. Book wouldn't answer. "But there are going to be some ground rules. I have something you want more than anything else, and I'm willing to share it with you, but in return, I don't want you going on a killing spree and making a hundred more horcruxes. And honestly, it wouldn't matter to your immortality if you did make that many... beyond the first few, I suppose."
"Why wouldn't it matter?" asked Mr. Book. "More horcruxes, more security."
"It doesn't work that way," said Mr. Silver, adopting a lecturing tone of his own. "Scientists call it fencepost security. After a certain point, making a high security wall even higher doesn't improve security. Any sensible attacker would just go around the wall, or dig under it, or break through, or fly over. Making the fencepost higher won't defend against any of that. While you were unconscious, and thiss iss not lie, I thought of three ways to bypass your system. Four, actually. Two of them I could have done myself, right away, without extensive preparation time or a cooperative enemy."
"How?" Mr. Book demanded at once.
The Dementor's kiss. Permanent insanity from prolonged exposure to the Cruciatus. A full memory wipe with Obliviate. Transfiguring his body into a solid object and maintaining that transfiguration indefinitely.
"Will tell you," Mr. Silver hissed, "if you promisse not to maim, torture, or murder ssmart creatures in thiss new place." For a brief moment, he switched back to normal speech. "And by 'smart creatures,' I mean sentient creatures." Parseltongue didn't have a word for 'sentient', and he didn't want Mr. Book to use the technicality of 'I am only bound not to kill smart creatures; he's a moron, therefore I can kill him.'
"Musst also promisse," Mr. Silver continued, "not to kill more than three ssmart creaturess in thiss place. Lasst, you musst promisse that when you kill ssmart creaturess, will only be to ssave more livess and to get rid of maliciouss menace. Know that iss pushing it, but in return, I will promisse to help fix flawss in ssysstem."
"Fencepost security or not," said Mr. Book, "you think I would allow myself to be limited to just three horcruxes in return for your aid?"
"Yess, for thiss iss alsso true: flawss in ssysstem are made worsse by extra creationss."
"Even if it is not to make a horcrux," said the thestral, "you know that I find it enjoyable to kill idiots. Do you truly think your advice is worth more to me than my favorite pastime?"
"Do you think it's not?"
"Yes."
"It's a risk to your life. I thought you'd want this information at almost any cost."
Mr. Book gave a dark chuckle. "Now that you've made the mistake of telling me there are at least four bypasses to my immortality, do you truly believe I am incapable of seeing them for myself, once I am able to devote my full faculties to the problem?"
"Yes."
"Ansswer in Parsseltongue."
"Posssibly," hissed Mr. Silver. He switched back to normal speech. "And I can prove it. Remember the last time I taught you something important? On your own, you didn't see my way of avoiding the mistake that cost you ten years of your life. Even after thinking for ten years straight about all the mistakes you ever made. You didn't see that you could have made a horcrux for someone else, kill them, and see what happened. You didn't see that you could have troubleshooted the system to make sure it was working properly. Even after I laid out a thought experiment that should have made the answer obvious, you still didn't see it."
The thestral was frowning heavily at this point.
"Your reasoning is impaired in ways that mine isn't, just as mine is impaired in ways that yours isn't. I think you'll see some of the flaws for yourself, but I doubt you'll see them all. Ask yourself what's worth more to you: your ability to kill as you please, or your life."
Mr. Book was openly scowling, as if he'd just been told that he was about to be tortured, but his torturer was giving him the pleasure of choosing his instruments of pain.
"From a logical standpoint," continued Mr. Silver, "shouldn't the choice be straightforward?"
"You severely underestimate the extent of common idiocy and the pleasure that comes from bringing a stop to it. I reiterate that you have not tried it for yourself. There is a sort of catharsis that comes from rooting out a weed at its source."
Mr. Silver was now scowling as well. "I don't need to try it to know that I wouldn't enjoy it."
"Is it so difficult for you to imagine the joy that comes from crushing pests?" the thestral asked. "Then instead imagine the relief of removing a pebble from your shoe after enduring it for miles of walking, or the satisfaction of swatting a fly that has distracted you from your studies for hours on end. I refuse to endure idiocy for extended periods of time, and your proposed trade would force me to do so."
"You don't have to endure it if you're smart about it," Mr. Silver argued. "Remember your own advice on how to deal with things you can't fight: apparate away. That works with idiots as well. Turn around and walk in the other direction. There's no need to kill them. Just don't associate with them."
There was a pause that stretched longer than all the other pauses that had come before. Over the course of what felt like minutes, Mr. Book's expression stayed at a mix between anger and disgust.
So Mr. Silver added one final remark to hopefully change that:
"You know, when an idiot dies, they'll never properly suffer the consequences of their own stupidity. They'll never see how stupid they were if you just kill them. No torture, no maiming, no murder, but you can still ruin them in a more creative way if you have to do something. Bankrupt and humiliate them, for instance."
The thestral's expression slowly switched from scowl to merely sour. Then it went from scornful to thoughtful, from refusing to interested.
"Very well," hissed Mr. Book. "If you tell me flawss and help to fix them, I sshall kill no more than three ssmart creaturess in thiss new place, unless more iss necesssary for my own ssurvival, or unlesss you approve of more. Creaturess I kill will be threatss to livess of otherss, and the world will be ssafer place if they die. I further promisse not to torture, maim, or murder, again unlesss I musst for my own ssurvival. Now tell me of flawss."
"One final consstraint," hissed Mr. Silver as he realized the potential problem. "One of creaturess you choosse to kill musst not be me."
"You ssusspect I intend to kill you?"
"Do you deny it?"
Mr. Book chuckled. "To repeat words you once spoke at dinner, I shall neither confirm nor deny it, but I could ask you the same question. Am I to believe that you intend me no harm?"
"If I did, I wouldn't have woken you up," said Mr. Silver. "But since you insist-" switching back to Parseltongue "-if you promisse not to threaten my life, I will promisse not to threaten yourss."
"Your deliberate choice is not required, Mr. Silver," said Mr. Book in ordinary speech. "The school seer recently prophesied vast destruction, and you are the one foretold to bring it about. I would not normally say this, especially to you, but I had planned to say it regardless. And before you foolishly object, remember that it is prophecy. You are an immense threat to the world, and the world would be an immensely safer place without you. When we spoke amidst the stars, this is what I meant. I sspeak truth."
Mr. Silver, who'd had to contend with predictions of becoming a Dark Lord many times by this point, almost continued that habit here. He almost reacted defensively. But then he remembered a certain quirk of psychology, a small detail that had stuck with him from one of the many books he'd read, though he couldn't recall which book had said it.
When you're on the defensive, you usually respond instantly, without even taking a fraction of a second to think about your response. It means you're acting on autopilot. You're saying whatever you need to say to absolve yourself of guilt, shame, suspicion, or some other negative social pressure. In short, you engage in politics, not rationality. You're not actually thinking. True thought takes more than two seconds. But lying to yourself doesn't take any time at all.
Once Mr. Silver realized that's what his brain was doing, he quashed the instinct to ignore the evidence and leap to his own defense, and started actually thinking.
Mr. Book is convinced he would become a massive threat – not to 'mere' countries, but to distant space probes. Mr. Book had been convinced by prophecy. That did count as strong and significant evidence in the magical world, and it was hard to argue against. Especially since he didn't know...
"What was the exact wording of the prophecy?"
A sardonic chuckle. "It would be the height of stupidity to tell you, Mr. Silver. When I heard a foreboding future about myself, I brought it about. I have no intention of repeating that mistake."
"If you plan on killing me anyway, what's the harm in telling me this 'foreboding'- actually, wait. I think I just guessed the prophecy. Erm, sorry."
"Oh?" asked a heavily skeptical voice.
"Yess."
Two memories had surfaced at the term 'foreboding prophecy'.
The first was a centaur saying the sky was about to be empty, then trying to slay him. The second was the school seer giving a prophecy to the entire student body of Hogwarts after the first week of school.
"He is coming! The one who will tear apart the very s-"
And then Dumbledore had taken the prophetess away.
Stopping a seer from speaking, according to the books, is ill-advised. It prevents Time's pressure from being released. Interruptions just delay the inevitable, kicking the pressurized can down the road until it eventually bursts some other time. And if that particular 'tear apart' prophecy had been released later, it was a good candidate for the one Mr. Book had heard.
So, who was coming, and what were they going to destroy?
Nearby students had thought the prophecy was talking about him. He'd quickly refuted the speculation, saying that he couldn't be coming there, he was already there. But now it seemed likely that it was referring to him.
But that still left the most important question: What was he meant to destroy? Tear apart the very what?
Back when the prophecy was first made, some students said the first letter of the next word was 's'. Mr. Silver overheard a student theorising Trelawney was about to say 'sun', and that everyone would be in trouble if that was the case. Mr. Silver remembered thinking to himself that was unlikely. Nobody in the wizarding world knew science-fiction theories on star harvesting. If there were wizards who knew about star harvesting, then you might have a problem, but wizards didn't think that way. He had neglected to realise that he was a wizard who knew about star harvesting.
Combine that with the incident in the Forbidden Forest where he was confronted by centaur – a species known for revering and respecting the night sky, a species that would wish no harm to befall it, a species that would probably kill anyone who was foretold to threaten it...
"I'm prophesied to tear apart the very stars, aren't I?" Mr. Silver suggested, summing up his speculation.
There was another one of those long pauses.
"I see," said Mr. Silver into the emptiness. "That's good."
"Good?"
"Yes, good. Great, actually."
"How in Merlin's name could that possibly be good?"
"Because it's a promising prediction about the future." Mr. Silver normally didn't think about this; it was abstraction to the extreme, and by no means a guarantee. Still... "It would be like if a prophecy predicted that a woodsman will tear apart the very trees in a forest, or that a nuclear physicist will tear apart the very atoms in uranium- actually, wait a minute, I can see why you're worried. A Chernobyl on the order of magnitude suggested by the prophecy would be bad." And come to think of it, that's probably the exact reason why Mr. Book was so afraid. "Still, if I ever do get to the point where I'm directing a star-harvesting operation, it'll mean our species has officially grown up. Even more so than it grew up when it replaced forests with farm fields, or when it started preferring nuclear energy over fossil fuels."
"And if you had been further foretold to end the world," Mr. Book inquired with heavy sarcasm, "and not just the stars? I suppose there is an optimistic interpretation for that as well?"
"Didn't you just say you wouldn't tell me the exact wording?"
"That was not the exact wording," said Mr. Book, "though now that you've guessed the most important part, I may as well tell you the rest. Working on almost-correct assumptions is far worse than knowing the exact prophecy. Many tales in wizarding literature are keen on this point." The thestral took a few deep breaths, then said, "HE IS HERE. THE ONE WHO WILL TEAR APART THE VERY STARS IN HEAVEN. HE IS HERE. HE IS THE END OF THE WORLD."
"The end of the world as we know it," Mr. Silver said at once, completing the cliché. (Thanks, in part, to a catchy muggle song with that refrain.) "The ancient hunter-gatherers would view the modern state of the Earth as the end of their worlds. The native populations of many colonised continents certainly saw the colonisers as enders of their worlds. And regardless of the evils involved in the colonisation process, it did end slavery- or tried to, anyway. At the very least, it eventually led to better living conditions for the colonised countries. So if I'm going to end the world, that's not necessarily a bad thing. I'll just have to be careful how I end it, and to avoid any critical failures along the way. If we promise not to kill each other, you'll be around to make sure that I don't mess up that bad."
"Do you truly expect," said a voice of skepticism and cynicism, "I would believe that particular prophecy foretells deliberate action instead of a dreadful mistake?"
"I don't expect you to believe it right away," Mr. Silver conceded. "You haven't read enough scientific literature. But think about it this way. The exact phrasing of that prophecy seems to suggest that I will personally be tearing apart the stars. And if I am going to do that, I'm going to be very selective about which stars I tear apart. Not important stars. Certainly not any stars that govern living planets. I'll probably start with stars that threaten living planets. Dying stars. Dangerous stars. Stars can go supernova. They can devolve into black holes, and those are some of the most destructive things in existence. We wouldn't want that to happen near a system containing life. Especially not our solar system. There are also plenty of rational reasons to go out of your way to destroy a star. Fuel for a futuristic rocket ship, for example. If we were escaping a dying planet, we'd need some way to acquire new resources. Stars are, essentially, giant balls of resources that have, unfortunately, caught fire and need to be scattered and put out. So yes, I expect you to believe that the prophecy might be talking about a choice instead of an accident. I just wonder how long it will take you to admit it."
There was another pause in the clearing.
"Well?" hissed Mr. Silver. "I will tell you flawss, and promisse to help fix them, but I await your oath."
And that was that. He'd given it his best. Explained it as thoroughly as he could. Nothing left to do but see how Mr. Book would respond to the argument.
Mr. Book decided to take his time. He closed his eyes once more, a picture of a person- or pony- deep in thought.
Mr. Book took so long, in fact, that Mr. Silver eventually got bored, asked himself if there was anything he should be doing in the meantime, and remembered that a letter had appeared out of nowhere.
He silently debated if he should read it. It was addressed To Harry, and it was written on parchment, so it must have come from Hogwarts. That was when he realized the letter might shed some light on the whole Mirror situation, so he decided to go for it.
Mr. Silver stepped back slightly, which rendered the parchment visible again, but since it was below grass-level, Mr. Book shouldn't be able to see it from here.
Next problem: opening the letter without making a noise. It was sealed and-
No, wait. Mr. Silver brought out his wand and brought it forward. As soon as he tapped the parchment, the letter folded open obligingly, as if asking to be read.
Mr. Silver glanced up at Mr. Book, who hadn't reacted to any of this, then back down to the page.
(The following is an excerpt from Chapter 119 of Methods)
Dear Harry James Potter-Evans-Verres:
If you are reading this, you have defeated Voldemort.
Congratulations on that.
I hope you had some time in which to celebrate before you opened this scroll, because the news in it is not cheerful.
During the First Wizarding War, there came a time when I realised that Voldemort was winning, that he would soon hold all within his hand.
In that extremity, I went into the Department of Mysteries and I invoked a password which had never been spoken in the history of the Line of Merlin Unbroken, did a thing forbidden and yet not utterly forbidden.
I listened to every prophecy that had ever been recorded.
And so I learned that my troubles were far worse than Voldemort.
From certain seers and diviners have come an increasing chorus of foretellings that this world is doomed to destruction.
And you, Harry James Potter-Evans-Verres, are one of those foretold to destroy it.
By rights I should have ended your line of possibility, stopped you from ever being born, as I did my best to end all the other possibilities I discovered on that day of terrible awakening.
Yet in your case, Harry, and in your case alone, the prophecies of your apocalypse have loopholes, though those loopholes be ever so slight.
Always 'he will end the world', not 'he will end life'.
Even when it was said that you would tear apart the very stars in heaven, it was not said that you would tear apart the people.
And so, it being clear that this world is not meant to last, I have gambled literally everything upon you, Harry James Potter-Evans-Verres. There were no prophecies of how the world might be saved, so I found the prophecies that offered loopholes in the destruction; and I brought about the strange and complex conditions for those prophecies to come to pass. I ensured that Voldemort discovered a certain one of those prophecies, and so (even as I had feared) condemned your parents to death and made you what you are. I wrote a strange hint in your mother's Potions textbook, having no idea why I must; and this proved to show Lily how to help her sister, and ensured you would gain Petunia Evans's heartfelt love. I snuck invisibly into your bedroom in Oxford and administered the potion that is given to students with Time-Turners, to extend your day's cycle by two hours. When you were six years old I smashed a rock that was on your windowsill, and to this day I cannot imagine why.
All in the desperate hope that you can pass us through the eye of the storm, somehow end this world and yet bring out its people alive.
Now that you have passed the preliminary test of defeating Voldemort, I place my all in your hands, all the tools I can possibly give you. The Line of Merlin Unbroken, the command of the Order of the Phoenix, all my wealth and all my treasures-
"No."
The single word wrenched his attention away from the page like a teacher saying 'time's up' to a student who hadn't finished their test.
"Your theory is just that. Theory."
"Huh?" Mr. Silver asked automatically.
"I will speak no binding promises that prevent me from stopping you if you become a threat. I will not gamble my own immortality."
Oh. Right. He was waiting for Mr. Book's response.
"It's not as much of a gamble as you think," said Mr. Silver. "Here. Read this." He pointed his wand, whispered "Wingardium Leviosa," and lifted the letter into Mr. Book's field of vision.
"Iss thiss a trap?"
"Not a trap."
The letter was seized from his magical grasp by the magical grasp of Mr. Book.
He hadn't gotten to the end, but he didn't have time to read more. Convincing Lord Voldemort not to kill him, or anyone else for that matter, took priority. If he could succeed, maybe the difference between their two different spirits wouldn't be so great, and they would be able to coexist in the same world.
"Iss thiss a falsse letter?" Mr. Book asked, eyes pausing in their scanning.
"It iss real, ass far ass I know. No trickss. Appeared when I woke you."
Mr. Book's eyes went back to scanning. "Did you finish it?" he asked eventually.
"No, but I got far enough to see that it confirmed my interpretation of the prophecy."
Mr. Book chuckled, eyes closing as his magic folded the letter. "You should have read more, boy."
Uh-oh. "Umm... why?"
"The note didn't happen to come with a wand, did it?"
"Why would it've?"
"Accio Elder Wand."
Something flew right past Mr. Silver's head, coming to rest in the air in front of Mr. Book.
"What was-" Mr. Silver began, then froze. "Oh, crap."
"Indeed," said Mr. Book, wearing an evil smile as his magic seemed to toy with the knobbed wood. "This is the second time your negligence has allowed me to acquire a Deathly Hollow. If we count your Cloak, that's all three. Does your foolishness know no bounds?"
"Crap," repeated Mr. Silver. "But... that's... I mean... how did it even get here?"
"The Mirror is obviously answering my desire to have it," said the thestral, still grinning. He chanted the Deathly Hallow locating charm once more, then tilted his head. "Interesting."
"Can the Mirror do anything while we're trapped here? Can it pull literally anything out of thin air?"
"No," said the thestral. "Probably not. In all seriousness, either the headmaster sent it somehow, or it was simply trapped. The headmaster did try to throw his wand and the Line of Merlin from himself at the last moment. If he failed to send them from the Mirror's field of influence, or if the Mirror 'remembers' what it sees, as you theorised, that would give the Mirror full access to the Elder Wand, just as it had access to your Cloak. If this letter was on the headmaster's person when the trap was sprung, that would explain how it arrived here. The Mirror could be fulfilling our desire to have strong evidence about the nature of the prophecy concerning you, using resources made available to it by the headmaster's folly."
Mr. Silver ignored the despair that wanted to fill his mind. Focused instead on what was actually important. "You just called the letter strong evidence," he said. "Does that mean you're finally convinced?"
There was a pause.
"Did the headmaster truly destroy a rock on your windowsill?" was Mr. Book's reply.
"Yes."
"Answer in Parseltongue."
"Yess, sschoolmasster desstroyed my sstone," hissed Mr. Silver. "Up until now, I always thought my pet rock died of natural causes."
"Do you know why he did it?"
"Um..." said Mr. Silver. He searched his memory for information relevant to 'pet rock.' "If we're using prophecy logic... I think it was so I would refuse Professor Mc- er, the Transfiguration Professor's suggestion to buy a pet owl. Losing my pet rock at age six was pretty traumatic, and I didn't want a repeat incident."
"Anything else?"
"Um... she tried to interpret a comment I made about my reasons for not wanting an owl as evidence of my parents abusing me, and that moment led to me learning a number of things about the wizarding world. Obliviation, for instance. It also made me angry, and my anger that day led to me figuring out that you were still around, which eventually let me blackmail the headmaster and potions master. Not to mention I began preparing for your return, and that was probably important..." Mr. Silver trailed off, eyes distant.
"I see," said Mr. Book. "Then to answer your question, yes. This letter is convincing. It neatly explains the headmaster's foreknowledge, and yet further explains why he did not outright win our war despite that advantage. His moral outrage might have insisted that I die, but prophecies concerning the world's fate would have directed him away from outright killing me."
"Um... why?"
It was hard to imagine a prophecy foretelling that Lord Voldemort was necessary for the world's survival. Well, it was hard to imagine for about two seconds. Then he remembered words spoken about two months ago in the hospital wing of Hogwarts: I have no great fondness for the universe, but I DO live there.
"I may have prevented a world-threatening disaster or two in my day." This was said in a casual tone, as if it were of no matter at all. "I certainly intended to end you, a great threat to the world, and any sensible wizard would have done the same if they heard that prophecy."
"Are you lying? Did you truly ssave world in passt?"
"Am sspeaking truth. Ssome world-ssaving meassuress are ongoing. One ssuch meassure activated two yearss after I wass vanquisshed. Would not have activated if I were killed. If we ever escape the mirror, look up the name Stanislav Petrov."
Russian, thought Mr. Silver. Does that mean he interfered with the Cold War?
"In your case," continued the thestral, "leave it to prophecy to leave out key details, only obvious in retrospect. I already believed that the world was not meant to last. I believed that any attempts at saving it would only delay the inevitable, that I could only survive by escaping somewhere else." Now it was as if he was speaking to himself, for his own benefit, not Mr. Silver's. "And then I hear a prophecy that describes that escape. I fail to comprehend what I have heard. I decide upon a course of action that would condemn me to a dying world forever." Mr. Book shook his head. "Merlin once said that Time makes a fool of any who try to subvert it. I should have respected his wisdom. I should certainly have respected him more than the lesser wizards who claimed it is possible to break prophecies, something Merlin never did."
Silence, in the clearing.
"So..." Mr. Silver finally ventured, "have you truly accepted thiss undersstanding of the prophecy?"
Mr. Book gave a massive sigh, the Elder Wand vanishing beneath one of his wings. "Yess."
"You're open to my offer? You still agree to the previous terms?"
Mr. Book repeated the previous promises in Parseltongue – no torture, no maiming, no murder, no killing more than three dangerous sentient creatures here, except under certain acceptable circumstances. All of this, conditional on Mr. Silver telling him the flaws in the horcrux system and helping him fix them.
"You promise not to kill me?"
"I promisse never to raisse my arm or magic againsst you unless you raisse your arm or magic againsst me." Then, as an afterthought, the thestral amended the promise, saying that practice duels and so forth wouldn't count as 'raising his arm or magic' against Mr. Silver.
Mr. Silver repeated that promise himself, completing the conditional oath.
"Now," hissed Mr. Book imperiously. "Tell me flawss in ssysstem."
"Obliviation," Mr. Silver said at once.
Mr. Book blinked.
"A complete memory wipe is effectively killing someone. We should find a way to guard against Obliviation, or to restore Obliviated memories."
"...I see."
"As for the other three methods, first there's the Cruciatus. Torturing you into insanity might have worked, but I don't know how to cast the torture curse. Plus, you might have broken free from the curse even if I did, using your great creation to escape. Either way, we should research ways to restore sanity to tortured minds, or ways to resist the Cruciatus, or ways to prevent insanity from prolonged exposure."
"Yes..."
"Next, there's transfiguration. You once said that my stealing the unicorn didn't set off the protective wards on the herd. You said that because the unicorn wasn't dead, only transfigured, it didn't trigger the death alarms. So if someone transfigured your body but didn't kill you, it might not activate your horcrux system. I don't know how this could be fixed, but you can probably just add a clause to the horcrux ritual, or something like that."
"..."
"Finally, there's that way you restored my worst memory to me back in January. I didn't find your wand, and I don't have access to a Dementor. But if I did, I could have put your wand next to a Life-Eater as an inescapable death trap. Also, if a Dementor found one of your creations, I suspect they could drain you through it. Maybe even kiss you through it. If we ever get back to the other side of the mirror, you might want to sever your connection to most of your creations, barring the Resurrection Stone and the voyager plaque. When there are ways to bypass the whole system anyway, more creations doesn't exactly make you safer. All it takes is one Dementor finding one of them. The more you make, the easier you make it for the Dementors. But I do admit that the benefit of surviving the death of your body outweighs the risk of making one or two extra. Unless, of course, you help me get rid of Dementors entirely. Then the risk would go away entirely. Oh, and I guess our current predicament also counts as neutralizing you, in a way, and it can be fixed by us escaping. So that's five."
Mr. Book nodded. His eyes were distant, his expression abstracted, and his words, when spoken, seemed to make up his mind. "Your reasoning is valid. I will think on it later. For now..." The thestral glanced around himself, then at himself. "Where are we?" he asked disdainfully.