Twilight glanced around nervously as she followed Cadence through a twisting corridor she could have sworn wasn't a part of the Castle layout the last time she was in Canterlot, desperately seeking some sign of normalcy in what looked like a Discordian construction of sound and fury turned matter and light. "C-C-Cadence?" she asked worriedly. "Are you sure we're...going the right way?"
"There's nothing to worry about, Twilight," Cadence replied easily, walking calmly forward with a glowing stone levitating before her of its own accord. "Just stay in my hoofsteps, and you'll be just fine. I have safe passage here, and as long as you're with me, nothing will trifle with you." She chuckled softly. "I have many friends here, and the one we're going to see would be most upset if any of the other residents interfered with us."
"O-okay," Twilight stammered, making sure to place her hooves in the glowing prints Cadence left behind as she walked, being as exact as equinely possible...which was pretty exact, considering the two of them had different size hooves. "But this doesn't look like part of the castle I remember..."
"It's not," Cadence replied readily. "We're in the Spirit World."
"What?" Twilight gasped out, stunned. "But...but the Spirit World is incredibly dangerous! Ponies who try to explore it often become lost, or blinded by the beauty, or driven mad by the dangers, or lose their faces and are devoured by darkness!"
"That's because most ponies who come here are unaware of - and thus don't obey - the rules of conduct," Cadence explained firmly. "This is my third visit to the Spirit World, Twilight, and I've come back safe every single time." She indicated the glowing stone. "Besides, I have a direct pass to exactly where we're trying to go."
"What is that stone, anyway?" Twilight asked curiously, trying not to think about all the dangers inherent in Spirit Walking that she'd read about the first time she asked Princess Celestia to teach her Astral Projection. She still had nightmares about some of the things that could happen, which was why she'd never experimented with it.
"I guess you could call it..." Cadence' voice trailed off as the mad swirls of colors and dangers solidified into soaring columns, delicate busts, arching portcullises, and shelves upon shelves upon shelves of books, scrolls, and sheaves of sheets. "...a library card," Cadence finished, smiling widely as she caught sight of Twilight's awed gaze.
"This place is amazing!" Twilight gasped out, racing from shelf to shelf as she examined the things on them, careful not to touch anything. "There's...there's just so much here! I could spend a lifetime just cataloging it all, let alone reading it!"
"Careful saying things like that around here," a good natured masculine voice called out from down the aisle. A fox slowly walked towards them, its figure blurring into that of an elderly man as he approached. "I said something similar when I first arrived...and was offered the choice to never leave. While a good life for one such as I, I feel you have too much holding you home...especially if Cadence brought you here."
Cadence blinked, tilting her head. "I...don't believe I know you," she murmured softly.
"Ah, where are my manners?" the man replied. "I am Professor Zei, former head of Anthropology at Ba Sing Se University-"
"Oh!" Cadence gasped out. "Aang and Sokka mentioned you! You're the one who told them about this place!" She paused, frowning somewhat. "I'm not sure if I should be happy to see you or not."
"I well understand," Zei replied. "My new employer felt much the same...but he found value in my dedication to scholarly pursuits...so he offered me a choice. Remain in the library for the remainder of my natural lifespan and only just scratch the surface of its contents...or become one of his Knowledge Seekers, with the duty of organizing and cataloging everything the others bring in, and thus have all of time to learn all contained herein." He shrugged. "The choice was quite easy for me."
Cadence chuckled. "And I take it the fact that all the other Knowledge Seekers were vixens had nothing to do with your decision?"
Zei had the decency to turn bright red. "While I didn't take it into consideration, it has made my stay far more enjoyable than I anticipated..."
Twilight glanced back and forth between the giggling pair worriedly. "So...I guess I should go meet the head librarian and apply for my own, uh, 'library card' then?"
"Probably," Cadence agreed. Reaching into her saddlebag, she pulled out a magically preserved fragment of parchment. "You'll need this though."
Confused, Twilight levitated it to her face. Unable to make out the writing, she worked a quick translation spell. "...the Darkest Day in Fire Nation History?" she asked, confused. "What am I supposed to do with this?"
"He'll know," Cadence promised, nudging Twilight along. "Just don't get so distracted by everything here you don't make it back in time to be Shining's Best Mare!"
"Right!" Twilight agreed, quickly taking the indicated directions to find the Head Librarian...only to skid to a halt as she found herself face to talon with the biggest barn owl she had ever seen, his white face staring down at her from far too high above her. "...umm...I'm looking for the...head librarian?" she offered hopefully.
"That would be me," the owl replied. "I am Wan Shi Tong, He Who Knows Ten Thousand Things, and this is my library. How did you come to be here, Twilight Sparkle?"
Twilight blinked, stunned. "Y...You know my name?"
"I know many things," Wan Shi Tong replied. "You did not answer my question."
"Oh, right!" Twilight chuckled nervously. "C-Cadence brought me here-"
"I might have known," Wan Shi Tong grumbled. "As much of a scholar as you are, she should know her pass extends only to her kin. I made an exception regarding it being for as long as my library was in the world where the pass was issued, since she left that world as well, but you are not her kin until she is wed." He sighed. "She probably intended to try and guilt me into making a special exception for you, but I well know how important sticking to the rules is for you."
Twilight nodded. "Yes. I want to earn my right to be here!"
Wan Shi Tong nodded. "Admirable. Have you brought a contribution to my collection, then? To prove your dedication to knowledge for knowledge's sake?"
"Umm...Cadence gave me this?" She levitated up the parchment fragment.
"Ahh. So she finally got Sokka to return the things he 'checked out' without permission." Wan Shi Tong clicked his tongue. "I wonder what he provided in the way of 'late fees'." He looked from the parchment to Twilight for a time. "...ah, so that is her intent. Come with me." Turning, Wan Shi Tong began to walk towards a particular section of the library.
Confused, Twilight did her best to follow...only to gasp at what she saw. An entire segment of the library had been torched, scorched black with fire. "Who would do such a thing?!" she wailed in despair. "Those poor books..."
"One who sought to use my knowledge to harm others saw to it that my knowledge could not be used by anyone else against him and his own," Wan Shi Tong growled. "I understand you know a spell to restore fire damaged books."
"Well, yeah!" Twilight replied quickly. "I live in a library with a baby dragon. I'd be an idiot not to. But it needs-"
"The only piece removed from this section is the fragment you hold," Wan Shi Tong explained. "Every speck of soot and ash that was once the books and scrolls held here remains here. If your magic is enough to restore them, I shall consider it your contribution. After all, preserving knowledge is just as important for one such as I as increasing it."
Nodding, Twilight turned her attention to the section, focusing on her magic and calling it forth.
As Wan Shi Tong watched carefully, three layers of magical focus built up over Twilight's horn, just as it had when she'd dealt with the Ursa Minor rampaging in Ponyville. While not the same type of effort as that task had been, this was plainly just as strenuous a working for the young unicorn. Much to his pleasant surprise, it was only a matter of minutes before the first book began to reform out of the ashes. As the first was completed, the momentum of the magic began to build, and the rest of the books swiftly took shape, returning to their places on the shelves as the wood restored itself and the scrolls rolled themselves back up, whole once more.
As the magic finished and Twilight slumped back, Wan Shi Tong examined the results. Eventually, he spoke up. "You could have left the sorting and cataloging to me," he pointed out mildly.
"Force of habit," Twilight gasped out as she caught her breath.
"Still, a most pleasing contribution," Wan Shi Tong confirmed, setting a small stone to hover in the air in front of Twilight. "This is your key to my library. It will respond only to you. You have permission to bring guests, but they must bring their own contributions if they wish to explore my library."
"Yes sir!" Twilight replied breathlessly, gazing at the glowing stone in awe.
"For now, you should probably get home and get some rest," he instructed. "It's a big day tomorrow, isn't it?"
"Right! The wedding!" Spinning, Twilight raced away, following her 'library card' back to Canterlot.
It would be more than a week before she wondered how Wan Shi Tong knew so much about her, though she came to the conclusion Owlowiscius had told him about her. The owl didn't deny it, so she considered the matter settled, no matter how much that amused her #2 assistant.