His independent search for the most powerful magic known to ponydom had failed. He'd sensed nothing magical within the easily-located Castle of Two Sisters. He had sensed something on the way to the castle – heard something, rather – which confirmed the story spoken by Sparkle, at least in part.
Now he camped at the heart of the castle, camouflaged in a corner of a central, regal room.
Disillusioned, not invisible.
Disillusionment might have been harder to cast, but it would be easier to drop. He wore the cloak in the forest, then tripped over his limbs when he reached relative safety and tried to take it off manually. There was a spell to remove clothes, but it was so obscure that he had not practiced it enough to do wandlessly.
He would need to speak with Nightmare Moon if she appeared, and he would not reveal his wand to an enemy who believed only unicorns could cast spells. Not until the critical moment. And although that enemy had not yet showed herself, if she did, and if he was wearing the cloak at the time, he would either have to stumble awkwardly or reveal his wand. Thus, disillusionment.
It was ultimately of little consequence. It's not like he'd brought the cloak to wear it.
His senses were extended.
He regularly cast 'Tempus' to check the time.
The sun was supposed to rise at seven in Summer, according to a partygoing pony he'd questioned before departure.
It was now 7:15 AM with no sign of the sun's shine.
Mr. Book decided he would wait five more minutes, then return to the village.
"That went well," said a voice into the seemingly empty room three minutes later.
Midnight purple fur.
Armor that framed bat wings and a long, sharp horn.
A flowing mane of starlight.
All of these spun into existence in a swirl of mist.
"Ah, my glorious throne," said a being who could only be Nightmare Moon. She approached the high seat. "How I missed you."
She sat down in her throne. Examined her surroundings. Hesitated as her gaze met what should have looked like an inconspicuous corner.
"Show thyself, intruder!"
There was a pause. Then there was a sigh.
"Must every creature be capable of seeing through that camouflage?"
His spell rippled and fell away like water.
"A thestral?" asked Nightmare Moon, surprise in her voice. Then, with sudden glee, "I see! Thou art no intruder at all, but a loyal subject, wishing to welcome thy queen upon her return."
Deciding that it was to his advantage to allow her to come to her own conclusions, Mystery Book said nothing.
"But how were thou camouflaged?" the royal mare asked curiously.
"I would prefer not to say," said Mr. Book. "Though I shan't deny it if you guess correctly."
"Did a unicorn perform the spell for thee?" the mare guessed.
"No," said Mystery Book.
"An enchanted artifact, then?" she asked, even more curious.
Not that time.
"No."
"Then what?" she pressed, suddenly frustrated. "Tell me! Thy queen demands to know!"
He weighed his possible responses for a fraction of a second.
"Apologies, my queen," said Mr. Book, executing what he hoped was a proper pony genuflect. "It is a personal policy of mine to never reveal a riddle's answer. Not unless the pony pondering it is utterly incapable of solving it on their own."
Nightmare Moon stared at the pony she assumed was her subject for a long moment. "Yes," she smiled. "I understand. It would be like asking me to relinquish control of the moon, or to never observe the dreams of my subjects. Thou hast my apologies, my lovely servant. I should not have asked thee to violate thy special talent."
His what?
"Rise, my subject."
He rose.
"What is thy name?"
"Mystery Book."
"That is a lie," said the winged unicorn, instantly and without a trace of doubt.
It was only then that he noticed a weak pressure on his mind, as if something – or someone – was attempting a magical probe. His Occlumency barriers, which were always at full strength regardless of time or location, did nothing to stop the invasion. An unknown magic was influencing or examining his mind state of mind, and he was defenseless against it...
"I understand if thou have had to hide in the past," continued the royal pony, "but thou will not lie to thy queen."
...but this pony believed he was her ally despite her probe.
Thus she did not know he intended to kill her.
Thus his thoughts were not being read.
Based on the context...
"Apologies again, my queen. The lie was a force of habit, as you correctly inferred. My true name is Riddle Tome."
"Better," the queen declared.
It was closer to his original name, thus less of a lie, thus less likely to set off the invasive magical lie-detection. 'Riddle Tome' almost felt like the name he was supposed to have in this place.
"Come forth, my subject. Let me look upon thee and thy cutie mark."
That could only be one thing.
So, it is called a cutie mark.
Of course.
Showing nothing of his former ignorance, nor of his current annoyance, he obeyed. He had made a pre-prepared portkey, now ready for activation upon the slightest trace of hostility. It was a risk to close the distance, but a calculated one. He stood, walked forward, and turned slightly.
Nightmare Moon stood from her own throne and approached.
"My," said the queen as she looked upon his 'cutie mark'. "That's quite detailed." She hummed appreciatively. "A beautiful rendition of stars... though not in a pattern I recognize." Her eyes narrowed, and he could feel her breath on his fur for a moment. But only a moment. "Tell me, my subject, what is the book supposed to mean? Oh, pardon me. I should not have asked for the answer."
Riddle Tome ignored the impulse to grin. What an excellent excuse.
"May I at least ask thy special talent? No, wait, I must guess. Hmm... is thy special talent asking riddles?"
"No," said Riddle Tome, "though I do enjoy composing and proposing them from time to time."
"How about... writing or reading books containing riddles?"
"No."
"Is it..." the mare's eyes lit with excitement. "Is it solving riddles?"
Why not?
"Yes."
It was a well-honed skill of his, therefore it was not a lie to answer affirmatively.
"Wonderful!" exulted Nightmare Moon. "Such a lovely talent. And useful, for I am pondering a riddle this very moment."
"Oh?"
"Yes," she said simply. Then, in a puzzled tone, "The thought occurred to me that my sister would not neglect to prepare for my return. And yet, mere minutes ago, the great and powerful Princess Celestia was easily dispatched, leaving her precious ponies to my eternal rule. Tell me, dear subject, canst thou fathom why she would allow herself to be defeated?"
"Perhaps," he said with a grin, "your sister believed it was finally your turn to take to the throne."
He could be charming. It was a disarming tactic, causing most to lower their defenses and offenses. In situations of true risk, like this one, he needed every advantage he could get.
"Thou hast a sense of humor, I see," said the queen. Then, in a challenging voice, "Or thou art unable to solve the riddle."
Riddle's eyes narrowed. "Possibility one: she believes her immediate defeat is a necessary step for your eventual demise. Possibility two: she arranged for someone else to do her dirty work and decided that a destructive battle would not be worth endangering her subjects, thus she allowed herself to be overcome. This would serve the dual purpose of lowering your guard. Possibility three: she did not allow it. You were simply that much better."
Nightmare Moon smiled at the compliment, then her gaze turned serious. "Yes, that does sound just like her. Unable to face me herself, she finds some drooling tool to play like a fool." The mare smiled cruelly. "Well, I shall defeat her heroes as easily as I defeated her." She threw her head back and laughed.
Rule Five, thought Riddle Tome. Never underestimate an unknown. If this were a story, that conceit would be her downfall.
In the silence that followed the evil laugh, Riddle considered his next move.
This interaction had dragged on longer than he'd intended. Could he just kill her now and be done with it?
Unfortunately, no.
She didn't seem to believe her actions would amount to mass murder. She believed Celestia's ponies were left to her 'eternal rule', thus implying they were not going to die in her mental model of the future.
This posed a major problem.
He was bound by Parsletongue promise only to kill a malicious menace, not just a stupidly dangerous one. He'd been forced to repeat that phrase, "maliciouss menace", out loud. He hadn't the first time, but it was imposed upon him in the final exchange of promises, closing the loophole that would have allowed him to kill the merely world-threatening Mr. Silver.
Not that he could have directly done that anyway. The curse he'd invoked upon himself and all Tom Riddles that would descend from him was still in effect. He'd arranged for Mr. Silver to finally be bound by the curse as well. Not threatening each other's immortalities was a mutual promise at last. The only problem being Mr. Silver now knew of the curse's terms, even if he didn't know it was a curse. That would make eliminating him significantly more difficult if he ever adopted that aim again.
At least there was still that other loophole.
The promises he'd made about murder had been conditional. An exchange. A trade.
He'd promised he would not murder if and only if Mr. Silver helps fix his horcrux system.
Therefore, once he fixes the flaws on his own (and he would be dealing with two of four soon enough) he would thereby free himself to kill as he pleases. The vow is only binding if Mr. Silver is capable of providing aid. Remove Mr. Silver from the equation, whether by death or mere ostracisation, and his freedom to do as he pleases becomes an inevitability.
This realisation had been the true reason he'd been able to tolerate the deal.
Did Mr. Silver truly believe the comment about creative alternatives to murder had swayed him?
Perhaps. Ordinary people believed what they wished to be true. Mr. Silver is not ordinary, but still susceptible to that common error. It was likely Mr. Silver had been tricked, but not guaranteed. Mr. Silver's facial expression had been beneath the cloak, unreadable at the time.
In the worst case, Mr. Silver saw the trick and manages to contribute before it is too late, making the vow against murder permanently binding... but even then, that vow only holds on this side of the mirror.
I sswear to kill no more than three ssmart creaturess in thiss place.
If Mr. Silver does help, it would simply be more incentive to escape. The moment he frees himself from this ridiculous trap shall be the moment he frees himself from the vow of non-violence.
But for now, for his immediate plans, he was still bound by all constraints.
He needed to prove the malice of the menace before him to continue.
"Your majesty?" Riddle Tome broached politely after a long silence.
The queen seemed distant, her attention somehow elsewhere.
"A question, if I may?"
The queen's eyes opened. "Yes, my subject?"
With precise and carefully composed wording, Riddle Tome asked the question that would make or break a great creation.
"Will you be increasing the glow of the moon during your eternal night, such that it could support the many lives in this kingdom which were previously sustained by the sun?"
The moment Riddle Tome uttered the word 'sun', the queen's demeanor changed. Her entire body darkened to pitch black, and when she spoke again, it was in a threatening voice. "Please tell me a subject of mine does not have a sun-loving face."
There was the menace.
Good.
Now all he needed was the intended and willful massacre.
He needed the malice.
"Not sun-loving," said Riddle Tome in a voice that did not betray his thoughts. "Sun-acknowledging. A riddle master must be capable of answering any riddle, even those dealing with... unpleasant topics."
The queen seemed to relax slightly.
"In this case," he continued, "that unpleasantness would be the fact that, without the sun, plants will wither and die. Cold-blooded creatures will freeze. Predators will find it far easier to prey upon your subjects. I inquired about the luminosity of the moon not because I love the sun, but because I fear the natural consequences of its absence. If the moon's glow could be increased, it would potentially solve all these problems."
"Thou ask me to turn my beautiful moon into a sun?!" the queen demanded. "Never!"
His grin widened further in imagination. She had not outright declared she would engage in mass murder, but this was reckless endangerment at the very least. That she would deny a reasonable alternative to the safety of her subjects out of spite for her sister bordered on malicious. He could feel the bindings of his promise loosen with the rejection.
"But you do have a plan for the plants, correct?" he pressed, her attitude not quite there yet. "You might not care for lizards or fish. You might not care for predator vulnerability. Given your name, you might even prefer for your subjects to have nightmares over dreams – as they certainly would without the proper regulation provided by the day/night cycle. But they need to be alive to have nightmares."
"They shall live!" she declared. "No harm could possibly come from an endless night!"
"The leaves of almost all plants convert the sun's energy into food," he said simply. It was a fact of Herbology. "Without the sun, plants starve and die. Without plants, your subjects would also starve and die. Do you intend to import food from the other side of the planet, where the never-setting sun ceaselessly scorches lands unknown while we enjoy your endless night here in Equestria?"
The queen's eyes widened when he said the words never-setting sun, then further as he spoke of scorched lands. Her coat seemed to lighten from black to purple, the colors wavering as she whispered the words, "Oh, no."
Potential regret? Riddle realised.
"I didn't think..." the queen said, then trailed off.
Merlin damn it.
Before the conversation could continue, the heads of both ponies snapped to the doors of the throne room, behind which voices could be heard.
The coat of the queen darkened once more. "I will not allow any part of this world to suffer an eternal day."
Damn, Riddle repeated privately.
"But we must languish over logistics another time. It would seem we have company, and it would not do for a queen to keep her subjects waiting."
Hmm... perhaps it was time for a different approach. Malice was more likely to reveal itself in the presence of perceived foes, not perceived friends.
"Would you prefer my help," Riddle asked, "or do you intend to deal with them alone?"
"Thou art a scholar, not a guard. I shall deal with this alone."
"Very well," said Riddle Tome.
The queen's eyes widened when he wandlessly disillusioned himself, but then her head snapped around as the doors burst open, revealing six determined ponies.
Words were waged...
A fight was fought...
Elements were empowered...
An outcome was observed...
"I've missed you too, sister," said the light-purple pony who had been Nightmare Moon minutes ago.
"Those thousand winters were very long," whispered the apparent ruler of Equestria. "I never imagined I'd face them on my own. I love you, Luna."
Riddle ignored the ridiculous crying from the room's residents in favor of a fleeting shadow, unnoticed by the unobservant.
His gaze and disillusioned body followed that shadow outside the castle and into the forest, where it manifested as a pure black pony. Many curses, insults, and likely expletives were exclaimed, followed by the pony's declaration that it would destroy Equestria, it would exact its master's revenge, all in the name of a somber something-or-other.
Riddle felt no resistance from his vow as he said, "Avada Kedavra."
Thus he made the first of his three allotted great creations, anchoring his mortality in yet another Deathly Hallow and fixing one of Mr. Silver's proposed problems.
Even if Dementors could drain him through his horcruxes, they likely needed to see them in the first place, and they would not see a cloak that hid the user from death itself. He had guessed that part of Mr. Silver's solution to the Azkaban breakout months ago.
This was why he had borrowed the cloak, and of course he would be giving it back afterwards. Mr. Silver was the only one he could trust, thanks to Parsletongue promise, not to use the horcrux against him. Mr. Silver might even resurrect him if it became necessary.
Furthermore, keeping any horcrux upon his own person would defeat the purpose of making them in the first place. One wayward Fiendfyre could slay him if he neglected to diversify his mortality anchors to different physical locations.
It took little time for the magic to take hold. He felt himself able to perceive the world around the cloak even as he perceived the world around his body. He further felt his newly integrated anti-transfiguration-stasis ward take effect in the ritual (two down).
But he also felt a soft tune touch the back of his mind, as well as a soft tingling touch the part of his body depicting a book and stars.
These were not expected parts of the ritual.
At a glance, he saw that his mark had updated itself to include a sideways eight on the bottom half of the right page.
But that was not nearly as important as a potential invasion to his mental privacy.
He listened closely to the tune, heard that it was a kind of magical frequency, listened far more delicately, attempted to match the pattern of his magic to that magic...
And he disappeared, more thoroughly and completely than he ever could have with ordinary spells.
A single word went through his mind:
Interesting.