Twilight met Luna in front of the Library that night, the Princess seemed as if she was happy the girl had actually showed up.

“Good evening, Twilight Sparkle. Shall we then?” Luna said. Twilight nodded and smiled. They entered together, the Librarian greeting both of them happily. Luna inclined her head, while Twilight returned the greeting, and they continued towards the sub-level. That was where the restricted section was, which Twilight was quite familiar with.

They reached one of the few blank walls that Twilight had always felt seemed out of place, and she found out why. Luna put her hand up to the wall and dark tendrils of blue, so dark it seemed black, creeped out of her hands like magic. It made Twilight uneasy. It gave off a very dark vibe, like it wasn’t supposed to be there. It wasn’t innately bad or evil, though, that much she could tell.

The wall seemed to fluctuate and sort of fade, barely revealing a corridor behind it. Luna stepped through it, becking Twilight to follow. The scholar had only the slightest of hesitation as she stepped through the incorporeal wall. Luna smiled and turned to walk down the very dark, torchlit corridor. The wall solidified behind them as they walked and they came to a massive opening.

Twilight stood in awe at the massive cavern that filled their view. Carved delicately into the stone was a massive spiraling staircase, spiraling downwards down the walls of the relatively circular chamber. Torches lined the stairway and a massive waterfall spilled down into a pool at the bottom. There was sunlight lighting up the water, but only barely, through where it fell through.

“Above there is the end of the river that naturally flows through Canterlot.” Luna said as she started walking down the stairs. As Twilight followed, she noticed that some of the torches were moving up and down the stairs and into or out of alcoves along them.

She was surprised when one of the torches came close enough to reveal a fox was holding it in her mouth. It bowed to Luna, and then to Twilight, before opening her jaws to have the torch return to an empty sconce on the wall. It spoke with Luna in a language Twilight neither understood nor recognized. It sounded light and sweet, and the fox used a series of noises to compliment her own speech.

As they spoke, the cavern darkened slightly and Twilight turned to see that the waterfall was no longer gleaming with sunlight, instead it was the pearlescent moonlight.

“This way, Twilight Sparkle.” Luna said. Twilight looked back towards her new mentor to find her halfway in an alcove’s doorway a few steps down. She rushed to follow her mentor and was amazed to find that inside of the alcove was what looked like a library.

“Each section of these libraries hold dark, evil, dead, forgotten, banished and lost magic and information. My sister and I agreed never to destroy information, no matter how terrible and horrific it is. We also decided that history should never be hidden, anything we don’t think the public need to know is in the restricted section above. Down here, though, I warn you. For now, do not attempt to learn anything that I or one of the helpers do not point out for you.” Luna explained.

“My name is Sirena.” The fox from earlier said from where she was sitting next to the doorway. Her voice seemed old and wise. “We all will serve the apprentice of the night just as we do our mother of the night, though very few of us know this tongue.” The fox continued.

“The helpers here are mostly foxes, but many other animals of intelligence have offered their service to this place. They gather information and act as librarians here, and so they learn quite a lot. They can answer questions if you know a language they speak. They all speak Sylvan, though, the language of the creatures of nature.” Luna explained as she perused one of the shelves, occasionally picking out a book or two.

“We all understand this tongue, though. If you need directions then those who can’t speak it can still lead and direct you. We all have hundreds of years of experience and knowledge, though, and we all love to share stories with those few that know of this place.” Sirena explained.

“Hundreds of years?” Twilight asked.

“This place is special, and binding yourself to it does more than just grant access. It is a process you won’t be able to complete until I return.” Luna started as she placed a sizable stack of books on one of the many tables, each of them with varying levels of age and wear. “These will give you a basic knowledge and understanding of what we will be doing and a bit of the magic I will be teaching you.” She continued.

“This one…” She started as she placed a tome bound in a sort of black crystal cover next to the stack. “...may never reach anyone’s eyes but your own. Only Sirena and the other Elder Helpers know what it contains, besides myself and Celestia. You will learn what it contains after studying each of the other tomes here.” She explained lowly.

“I probably don’t want to know, but what would happen if someone did? Spike has a tendency to read over my shoulder when I’m studying.” Twilight asked as she eyed the tome.

“That won’t be a problem, you won’t be physically reading this one… but if he ever gained access to that knowledge… I won’t scare you with the details but let’s just say Nightmare Moon is as much of a threat as Pinkie Pie’s alligator in comparison to those who have not answered the Night’s Call. This place is more dangerous than the dragon lands are for an elk for those who lust for knowledge.” Luna answered.

“I understand.” Twilight said after a moment of silence. It scared her, and Luna could tell, but she still didn’t regret the decision.

“Good. You won’t be able to access this place on your own, but there are usually helpers in the library above if you know where to look. My Nightguards answer to you as well, now, and they all know of this place. If you can’t find a helper, they will assist you any way they can. I know how well you treat my sister’s guard when they serve you, the Nightguards will relish the chance.” Luna explained as she turned towards the doorway once more. She said something to Sirena, who nodded and dashed out.

“I must leave now, you should see me off.” The Princess said. Twilight smiled and nodded, following her mentor. She was surprised when Luna started downwards and was awestruck when a pillar rose from the pool at the bottom. It looked like there was a series of doorways along it as it slowly crawled upwards. The water of the waterfall rolled over it as if it was nothing and stone walkways slid out to meet the massive construct.

“You will come to learn where each of these leads in time, but I implore you never to enter one of them until you do so. There is information on this spire in the books I gave you.” Luna said as she walked down one of the catwalks and stopped before the door. Twilight heard her whispering something and what looked like blood seeped from the thing and created a veil in the doorway in front of her.

“Farewell, Twilight Sparkle. I look forward to my return. I’ll send word before I return, it shouldn’t take longer than two weeks.” Luna said. Twilight nodded and raised a hand in farewell. Luna smiled and walked through the crimson veil, disappearing completely. The only magic Twilight detected was faint, coming from the spire, and it felt very old and as if it probably shouldn’t be there.

“Twilight Sparkle, it’d be best if you returned to the stairway.” Sirena’s voice came. Twilight looked back from where she was halfway down the catwalk to see the fox sitting on the stairway with a torch floating above her. Twilight nodded and stepped back onto the stairway. As soon as she did, the catwalks retracted and the spire returned to its place under the pool.

“I am aware that you return to your hometown in the morning, correct?” Sirena asked. Twilight nodded. “Please form a magical link with me, similar to yours with Celestia, and I will guide the link into the correct magical form to allow me to send the tomes through the link when you return. We cannot allow this information to be transported normally.” The fox asked politely. Twilight nodded and did as she was asked.

She was surprised when her magic was guided by what felt like an ancient presence, similar to the princesses, into the correct form. After a moment the connection went dormant and the magic stopped.

“Thank you. You may leave whenever you wish, there are sleeping quarters here as well if you wish to use them. This place is now another home for you.” Sirena said. Twilight smiled.

“I think I’ll return to my room now. I need to be up early to be on time. Thank you for your help, and I look forward to working with you and all the other helpers in the future. I should be back in Canterlot next week.” Twilight said.

“Then I will look forward to your return, Milady.” The fox said, bowing low. Twilight inclined her head in return. “I suppose I should help you leave, though.” The fox continued. Twilight giggled and nodded.