The tunnels under the castle were dark and cramped. Unlike most of the tunnels under Canterlot, these were carved from the very rock. Twilight was up front leading him deeper and deeper into the pony made cave system. Her horn was alight and casting a cone of light far ahead. Acropolis carried his small guard lamp hung around his neck. The cheap lamp barely cast any light making the halls seem even darker. As they went deeper he noticed that the darkness was becoming more and more oppressive, as if something was squeezing the light out of the halls. It was getting to the point he could barely make out Twilight ahead of him. Even sound seemed to get sucked away as they went deeper, at a certain point Acropolis could barely hear Twilight's hoof-steps, even though she was right in front to him.

They came to a large dark wooden door of which their lights barley lit the whole surface. It was the most imposing door he had ever seen, its large metal hinges looked like they held the wood of the door prisoner. In the middle was a massive crescent moon with two swords crossed behind it. He was in awe at this sheer display of dominance. These Lunar guards commanded respect even in their doors. He wished he could have been around to meet them.

“This is the Lunar wing of the castle,” she opened the massive doors with relative ease, confirming in his mind that she didn't really need him there. “It’s windows face out of the cliff towards where the moon rises so they could observe Luna's work.” she led him deeper into the massive chamber. It was mostly empty as if it had been cleared out in quite a hurry. They had left only a few shelves and benches strewn about, truly no-pony has been here in some time. “Some of the books I have read say that they observed the moon and Luna with god-like respect and prayed in this room facing these windows as she raised the moon." She smiled as she gave her mini lecture. "They believed that basking in her glow would give them strength to defend her and the kingdom.” Twilight was half way across to room when she noticed that Acropolis was not beside her. She turned around to find him bowed before the grand windows basking in the light of the moon, offering his humble prayers to the moon. “Yes, just like that,” she said with a  smile, “come on Acropolis, we have much to do.”

“Coming Twilight.” He felt better, stronger even, he even felt more confident. Maybe Luna’s moon really did give back if you offered it a prayer. He smiled with the thought of it.

Following Twilight through the abandoned chambers they soon came to the grand lunar library. Many books were still on the shelves. Acropolis took note that the shelves were carved out of the rock, and that books were in surprisingly good shape for being  over a thousand years old. Walking to the center of the room Twilight sparked her magic and lit the many torches that were strewn about. Clearly she had already been sorting the books by subject and size for easier transport, judging from the neat piles of books all around the room. In the new light he then saw the ceiling and the carvings it held. Above him was a massive mural of Luna and her guard fighting monsters from the Everfree forest. The depiction of this massive battle covered the entire ceiling. The figures of the sculpture seemed to be reaching down as if asking him to join the fray. He stood there staring up at Luna’s upside down face. He took exception of her expression, it was not one of combat. She looked as if she was having fun while deep in the thralls of battle.

Come. The voice echoed through the room. A chill ran up his spine.

There it was again, but louder, its was the voice from the bridge. He spun in place looking right at the doors across the room from him. Going into full defensive mode he pulled his wings forward like a shield. A ability he developed for his wings to serve him in combat rather than flight.

“What is it?” Twilight called as she joined him the middle of the room, her magic ready for combat, wings spread wide.  

“I heard a voice, did you hear it?” he asked her while never taking his eyes off of the door.

“No, I didn't hear it, did it come from the barracks?” she asked. He simply nodded. She leaped and soared quietly over to the door, landing just next to it. Moving closer he pulled his massive wings forward maintaining his shield. She looked to him, he nodded  again, and she threw open the door with her magic. Using his wings to thrust himself forward, he burst into the room. The room was empty, and quiet. The massive windows made the moon look as if it was just outside. Acropolis came to a sliding stop in the middle of the room. His eyes darted around, searching for something, anything, that could have made a noise. Something to justify this feeling he had. Twilight entered the room looking about, casting her light spell in to the cracks the natural light didn't reach. “Nothing here.” She said dispelling her magic.

“You sure you didn't hear that?” he asked folding his wings back up, the twitch and snap of his wings folding was audible to Twilight. There was only one other door in the room and he stared intently at it. The crescent moon on the door seemed to suck the light out of the room.

“No I didn't hear it, Acropolis,” she folded up her wings, “What was it?” she walked over to stand next to him.

“A voice, it said come,” his eyes didn't waver from the door, “What’s in there?” he asked motioning with his head towards the imposing door.

“That is the Lunar Armory, but there is no way any pony is in there,” she said as she walked up to the door and grabbed the handle with her magic, “It was enchanted by Princess Luna thousands of years ago,” she pulled with all her might and the door held fast, “Only her or her guard can open it, and since the Lunar guard is no more, only she can open it.”

Open. He heard it with such clarity it was if Twilight herself had said it,

He would have flinched but by then he had figured it was just his mind playing tricks. He convinced himself he was psyching himself up about being in the Lunar Guard chambers. He dismissed it all as the forest playing its tricks and they went back to the library. There was still much work to be done. They worked all night pulling books out and pilling them up in the throne room for later transport. When the sun began to rise Twilight decided to stop. Agreeing to reconvene the following night they parted ways and Acropolis went home.