The sand poured in and the building itself shuddered, as it was ripped from the material world with an ear-shattering, calamitous sound like grinding stone. Finally, with a creak, the library settled. A fox whimpered.
"It's for the best." Wan Shi Tong assured his assistants. "Those humans do not deserve-"
A tiny sound. A shuffle of some sort. A human footstep. Wan Shi Tong stopped mid-sentence, his hearing being horribly precise, and instantly craned out his neck to find himself angrily face to face with the terrified Professor Zei.
"You." he growled.
"Hello there." Zei smiled, nervously, reassuringly, in the way one tries to convince someone they are not a threat.
"You didn't leave with the others?"
"N-no, great spirit."
Wan Shi Tong tilted his head in a way that must be recognized as curious, but it went farther than any true owl or human's neck could stretch, and to Zei it looked broken, alien, a little menacing.
Wan Shi Tong spoke only one word. "Why?"
"I-I couldn't-" He could not seem to find the right words. He was holding a stack of books tightly to his chest, gripping them as if for dear life. "I came here to learn. I needed more time."
Wan Shi Tong narrowed his eyes. "You are lying, like those others were. Humans only seek knowledge in order to take power over other humans." He retracted his neck, so they were no longer nose to nose, giving Zei room to breathe. "No matter. You are trapped here now, do you understand that? You will never return to the physical world, never see other humans again."
The professor gulped. "I understand."
"I do not think you do. I should kill you as punishment for your deception, but I will not. If humans want to use my library so badly and yet so consistently abuse it, I think this shall be a fitting end." He puffed up his feathers, and his voice boomed. "You will have your wish, human. I will give you time. You may read the materials here to your heart's content, but they will be of no use to you. You will never be able to abuse your findings, nor share them with other humans, for if you venture outside these walls the other spirits will surely be less kind than I. This library will be your tomb, but until then, you may browse. Let no one say that I am cruel."
"Thank you for your mercy, great spirit." Professor Zei bowed deeply, and held there for an awkward moment too long, waiting for the spirit to say something.
Wan Shi Tong ignored him.
Zei, quietly, carefully, backed away and returned to his studies.
Professor Zei spent the next few days, or what he could only assume were days, immersed in books and scrolls. The sun never rose nor set here, and while underground the library had been dim and stale it now was flooded with light and air at all hours. It was easy to get lost in, full of long staircases that went to tall spires, shelves and archives that stretched farther than eyes could see, and a thousand hidden cubbyholes full of comfortable reading chairs. He tried to explore enough to get a feel for the place, design a map, but the place was so terribly massive, he realized, that such a feat would be nearly impossible. Art of all styles and eras lined the walls and the different wings were marked by grand white archways, many now cracked and aged. He could imagine, long ago, when it was full of life, what a beautiful place it must have been. He crept around carefully, avoiding Wan Shi Tong, taking things from the shelves and then ensconcing himself somewhere to read for hours. He had a million burning questions to ask the bird, but he knew better than to attract his attention.
He was searching for a particular scroll in the section on pre-unification Earth Kingdom agronomy when he saw something peculiar just outside a window.
It was a tree, with fruit hanging off it, but the tree was strangely colored and the fruit was something he could not recognize. The strange light, not quite sunlight exactly, that flooded the place framed it. What an odd thing. Before he knew it he was reaching out to grab it, and wondering where in the library he might find a reference guide to identify it, and-
A voice came from behind him. "I would not do that if I were you."
He turned to look at Wan Shi Tong, perched and watching him intently.
"This is the spirit world." he continued, "It is not made for the likes of you. Many beings outside that window would be quite willing to end you, and eating unfamiliar things is likely to do the same." He paused. "Besides, you cannot possibly be hungry."
Zei realized he was right; he had not eaten or slept in what must have been a week, but felt no need to do either.
He laughed. "Quite right! I suppose my natural curiosity got the better of me. Thank you for your wisdom."
"What are you reading?"
"What?"
Wan Shi Tong nodded at the books he was holding. "Your studies. What have you been reading?"
"Oh, this? This is just some light reading, for a break." Zei's trepidation all but disappeared as soon as he was asked to talk about his work. "I'm an anthropologist, you see, so what I've really been studying lately is cultural divergence between the northern and southern water tribes, the isolation over time has caused a significant number of changes, it's very interesting."
"Have you looked at the Foggy Swamp Tribe?"
"The what?"
"The third water tribe, in the swamp near Gaoling."
"There's a third water tribe?!"
Wan Shi Tong nodded. "Yes, though it's widely unknown. Rather isolated, the others don't seem to be aware of it's existence either. Their oral history and some of their bending movements strongly suggests they're descended from members of the southern tribe, though several centuries ago. The unique environment and seclusion has allowed for the development of a wide range of changes in dress, diet, and bending, as well as linguistically-they have very distinctive accents." He paused. "Fascinating, is it not?"
"Indeed! Do you know where I can read about this?"
Wan Shi Tong made a clucking noise, and a fox popped out immediately. "Show him." He ordered.
The fox quickly ran up to Zei, who gave it a scratch between the ears. "Thank you very much!" said Zei with a bright and cheerful smile to the spirit who could kill him whenever it wanted to, and had threatened to do so multiple times, as he followed the little helper off towards a new set of shelves to spelunk.
After that, Wan Shi Tong noticed, Professor Zei no longer snuck around the library. If he wanted to look at something and Wan Shi Tong was already in the room, he would simply walk in and do so with a nod and smile, and only the slightest bit of hesitance.
Once, after what must have been months, Wan Shi Tong caught him examining a lion statue that sat in the eastern wing. "What is it exactly you are doing, human?"
"Ah, yes! I saw this lovely piece here, and I thought, well this style looks so familiar. And I thought about it for quite some time, and I realize it seems exactly like those of Xiulan-"
"...the famous sculptor, yes, from roughly 400 years ago. She made it using reference materials she found here. Very nice woman."
"You knew her? Incredible! Can you tell me about her?"
Wan Shi Tong tilted his head. "You know, I did not expect you to last this long."
"What do you mean?"
"I was certain when you came to fully understand your fate, you would try to escape, and meet your doom in the spirit world. Perhaps by having your face stolen, or eaten by a glowworm. Yet you remain stolidly within these walls. Why?"
"Why would I want to leave? I have access to everything I've ever wanted to learn, and so much time to do it! You have given me a great gift, spirit. I cannot thank you enough for it."
"...You are a very strange human. Very well. I will tell you about Xiulan."
"Oh! Wonderful! Let me get something to write it down on-"
At some point they fell into an odd sort of rapport. Zei read and re-read and found endless fascination in everything from Air Nomad architecture to sandbender textile development. Wan Shi Tong chatted with him on occasion, about history, art, technology, philosophy, or whatever he was reading at the time. At some point he stopped calling him "human" and switched to "professor," something Zei was happy to notice and knew better than to comment on. The assistants seemed to have a fondness for him, Zei certainly being more apt to give head scritches than the spirit, and one or two could frequently be found curled up nearby wherever he'd decided to work that day.
"Good morning, He Who Knows Ten Thousand Things!" he shouted, with an enthusiasm Wan Shi Tong and his assistants were very used to by now. "It always seems like morning here, doesn't it? The light never changes! I was never a meteorology man, but perhaps I should look into some spirit world weather patterns, since I'm here." The foxes had brought the newest pile of acquired knowledge for Wan Shi Tong to examine, and, as had become the habit, Zei as well. "What have they brought us this time?"
Wan Shi Tong did not acknowledge the 'us.' "Hmmm. A few things. Some updated maps, now that the Earth Kingdom has finalized it's post-war borders."
"Much needed! So much of your atlas section is just terribly out of date."
"I know, I know, you've told me. Perhaps if humans could stop fighting over dirt for a little while, I could have a map that remained accurate for more than 100 years." He continued, dry as ever, "One of your colleagues at Ba Sing Se seems to have made a breakthrough medical discovery, if that interests you."
"Oh?" An assistant eagerly ran up and gave him the scroll. "Did you steal this right out of poor Li's office for me? Why, you little rascal!" he laughed and the fox swished its tail proudly. "Yes, that's very worth reading. Hope he has another copy. Goodness, I need to put something together myself, but I fear I'm running out of paper."
"Paper? What on earth for?"
"Well, I've been synthesizing some research on theorized Air Nomad agricultural methods, and I think I'm on to some very good ideas. I must put it down somewhere, you know? A good, well-organized review to put everything together, to start, and then developing something of my own. I've learned so much! It's been too long since I published a decent paper."
"Publish for whom?" Wan Shi Tong's tone grew darker, quieter. "It will never leave this library. No one will ever read it."
"I know, but writing it down will help me get my thoughts in order, won't it? A great work is worthwhile all on its own. Really, I can hardly call myself an academic if all I ever do is read what other people are saying." He smiled. "I can simply let the library have it, when I'm done."
"You would give your work to me?"
"Seems like the only right place for it, don't you think?"
Wan Shi Tong said nothing, and went back to examining the latest arrivals. Days later, though, a fox would deliver to Zei a hefty stack of parchment and three bottles of ink.
It cannot be said that any particular person has contributed more to the great library than any other. Some creators are more prolific, certainly, but the value of knowledge cannot be measured merely in quantity. It can be said, however, that during his lifetime Professor Zei contributed 17 books, 400 papers, and an incalculable number of additional notes, reviews, summaries, and sketches on a wide array of topics, all of which were readily accepted by the spirit himself.
Wan Shi Tong was not a spirit prone to high praise, particularly for humans, who had so recently betrayed him. He took most of it wordlessly. When he finally commented, to say that Zei's analysis of cross-cultural transmission in the Earth Kingdom colonies was 'innovative,' Zei thanked him graciously and tried not to beam.
He kept working even as Wan Shi Tong noticed his hair had turned gray and his face had grown weary. When he could no longer move around the library as quickly or easily as he used to, the worried assistants took to doting on him, readily bringing whatever he asked for and letting him rest his head on their soft fur. His demeanor never faltered, ever gregarious and eager to learn. He was so industrious that he managed to read nearly a third of the library, and even into his old age was still finding new hidden spires, new topics to explore, new theories to commit to paper.
Professor Zei, head of anthropology at Ba Sing Se University, died an old man, sitting on the floor and leaning against a shelf with books still open on his lap. The library, empty, quiet, hollow, once and for all belonged to the spirits alone. No more humans would walk its halls or read its stories.
The assistants, looking at each other from across the library, lifted their snouts to the air and began to howl and wail.
"I know." said Wan Shi Tong. "I liked him too."