Dumbledore stood before the bookshelf, one finger resting on the page.
Merlin Ambrosius.
That name had appeared in two different eras at once. One was the Middle Ages, in the age when King Arthur still lived. The other was on a Hogwarts Book of Admittance entry from just after the school's founding.
That was a gap of at least five or six centuries crossing over itself, the sort of paradox no one had ever been able to explain. For generations, Hogwarts Headmasters and Headmistresses had tried and failed to unravel it.
How could the same man appear in two separate pieces of established history? And why, at the very beginning, had the four Founders failed to realize that the legendary Merlin had come to Hogwarts as a student?
For years, it had remained an unsolved mystery.
But now, as Dumbledore's mind raced, he felt as though he had finally found the answer.
Yes.
The answer.
If Merlin's bloodline, the one he had passed down, truly could grant a person the power to cross time and distort history, then suddenly everything could be explained.
"Magic responds to the deepest desire in a wizard's heart."
"If Merlin, as a child, longed for a safe place to study magic, then perhaps his power truly could have carried him forward several centuries, straight into Hogwarts."
"He studied at Hogwarts first, and only later rose into legend in the past. That is why the Founders did not realize who he was when he first appeared."
"Perhaps, from Merlin's point of view, time was never linear in the way we understand it. At the moment he attended school, he had not yet gone back and become a legend."
"Only after he experienced that rise himself did later generations begin to know his name. That is what created the paradox between the two historical records."
The more he connected the pieces, the more excited Dumbledore became. His hand began trembling again.
And by now, Snape's patience had run out.
"I cannot be bothered with your nonsense any longer, Dumbledore. You have finally gone senile. I am leaving now, and I may as well swear myself to the Dark Lord again, younger and stronger than before."
His voice was sharp as a blade as he turned for the door.
It was not what he truly meant. It was simply the only way he knew to provoke Dumbledore into speaking.
"Severus."
Dumbledore's voice came from behind him, exactly as expected. It was quiet, but perfectly clear.
Snape stopped, though he did not turn around at once.
"I will tell you what happened. But you must choose to trust me."
Snape turned back.
His expression had the look of someone who had been holding back for far too long and was now one step from explosion.
"So in your heart, I have never truly trusted you? Then tell me this. What exactly was it, if not trust, when I came to you the moment I learned the Dark Lord had returned?"
"Am I not trusting you enough already? Am I a joke to you?"
He was not especially shrill, but the resentment inside him had plainly overflowed.
"I do not doubt you," Dumbledore said.
He rose from behind the desk, came around it, and stopped in front of Snape.
"I trust you more than I trust most people. Precisely because of that, I needed to be certain. What is happening now may go beyond anything we have ever understood."
His tone was serious, sincere.
Snape felt some of the pressure ease, though he still frowned.
"This has something to do with the Dark Lord reborn in that boy's body, does it not?"
He had already guessed as much. All of Dumbledore's strange reactions seemed tied to the one thing at the center of Hogsmeade's latest disaster.
The owner of that so-called Ten-Thousand-Souls Banner.
Dumbledore nodded.
"A moment ago, you asked me whether the Dark Lord had defeated Death."
"I can now give you the answer I did not finish before."
He paused.
"Defeating Death? I do not think that is impossible."
Snape's eyes narrowed.
"We both know how powerful the Dark Lord is. That is why he became the Dark Lord in the first place, is it not? Because he could not be beaten."
The wording had changed completely from before. But it fit the dread already growing in Snape's mind, so he did not question it.
"How are we meant to face that?"
Snape's brow remained furrowed. He wanted an answer.
"If he could be defeated head-on, he would never have become Voldemort," Dumbledore said evenly. "So we will have to outthink him."
His expression never changed.
"For now, do exactly what he expects. Earn his confidence. Continue following his instructions. In other words, continue infiltrating my side."
"Fawkes has already been lured over, but that is part of my design. You need not concern yourself with it. You need only remember, under any circumstances, that he is Voldemort."
Dumbledore emphasized that point again.
Snape frowned even harder.
"What do you mean, under any circumstances, I must remember he is Voldemort?"
The familiar feeling had returned. The old Headmaster, calm and calculating, was back.
And yet the content of his instructions made no sense at all.
Snape felt as though his brain had begun failing him again. If that boy was not Voldemort, then who was? There could not possibly be two Voldemorts walking around.
Dumbledore saw the confusion and chose not to explain.
"Voldemort is pathologically suspicious. He may well use a false Voldemort to test your loyalty."
"After all, he was my student. I know his paranoia better than anyone."
"Severus, simply do as I say. Leave the rest to me. I will arrange everything."
The Headmaster spoke with absolute conviction, his eyes deep and unreadable.
If history could be twisted, then perhaps it could also be deceived.
Dumbledore did not know for certain.
He simply intended to follow the boy's clumsy joke to its conclusion and see whether, by another route, he could erase the disaster called Voldemort from the world.
And, perhaps in the process, verify the existence of that power which could bend fate itself.
"Do you truly know what you are doing?"
Snape looked into those eyes, trying to read something there.
He saw strategy. He saw certainty. He saw an old man in the middle of an enormous game.
But he did not see the answer he wanted.
"I am moving toward success," Dumbledore said softly. "And I intend to arrive there."
There was something extra in the words, something Snape could not quite grasp.
But for some reason, it reassured him.
"I hope so. Too many lives are riding on you. Do not disappoint us."
At last Snape nodded, accepting the task.
Still carrying his doubts, he turned and left.
The door shut.
The office fell silent.
The former Headmasters and Headmistresses on the walls began whispering among themselves.
"You. What exactly are you doing? We all know Voldemort cannot possibly have been reborn as a child."
One old man with an arrogant expression spoke first.
Dumbledore did not answer.
"I am taking everything away from Voldemort," he said at last, "while also doing what I must."
He rose, crossed to a cabinet, and opened it.
Inside sat a mirror.
The Mirror of Erised.
...
At the same time, far below Hogsmeade, inside a foul sewage tunnel.
A young wizard was crawling on hands and knees.
"My lord, are you certain this tunnel really leads into Hogwarts?"
His voice echoed down the pipe, full of fear and desperate expectation.
"Yes."
The voice from the back of his head sounded hoarse.
"Dumbledore will never imagine that I would slip into Hogwarts through a forgotten drain and take the Philosopher's Stone he hid there. Once it is mine, I will truly return. When that happens, your service will be praised by every Death Eater."
Voldemort was drawing castles in the air again, as usual.
The young man's eyes lit up.
He crawled faster. His knees split open, blood mixing with the filthy water, but he did not seem to feel the pain.
His head was full of images.
Death Eaters cheering.
The Dark Lord rewarding him.
All the people who had once looked down on him, now kneeling at his feet.
"Thank you, my lord. Thank you, my lord."
Driven by dreams of future glory, he crawled with renewed vigor.
Then the pipe ahead split in two.
And then...
"What is that? Merlin's beard!"
The young wizard froze in shock.
Ahead of him, gathered in the tunnel, was a swarm of rats.
Large rats.
That point deserved emphasis.
They seemed to be holding some kind of meeting.
Or perhaps worshipping a statue.