Zuko slammed the book shut and shoved it back on the shelf. "Nothing."

Iroh frowned. "Zuko—"

Zuko stomped past his uncle to the next shelf and pulled out a fresh pile of scrolls and books. He already knew what Iroh was going to say, and he didn't want to hear it. The Fire Nation section had been burnt to ashes. At his uncle's suggestion, the two of them had backtracked to the room where information on bending and the previous Avatars was stored, hoping to find some records about the Children of the Undying Fire. So far, fire healers had not even been mentioned. It was as if the Children of the Undying Fire had never existed.

"There has to be something," Zuko muttered, flicking through the pages of a book in a feverish manner. Finding nothing of value, he tossed the book aside and picked up a scroll. "People just can't erase history. There has to be something."

Iroh sighed and closed the text he had been reading. "Zuko," he tried again.

Zuko wasn't listening. He scanned the scroll in his hand—a drawing of a creature that looked like a lion crossed with a turtle—and then rolled it up again in disgust. He was already reaching for the next book on his pile when his uncle's hand closed around his wrist.

"Nephew, stop," Iroh's voice was sad and tired. "I do not think you will find what you are looking for here."

Zuko hunched his shoulders. "You don't know that. There are still plenty of shelves that we haven't searched."

"And normally I would be just as optimistic, but the fact remains that we have searched all of the shelves dedicated to firebending. Don't you find it strange that there was no mention of fire healing in any of the texts?"

Zuko's chest tightened. Of course he had noticed the omission. He had just preferred to dismiss the matter from his mind. Wan Shi Tong's library was overflowing with ancient records. It seemed ridiculous that such a fountain of information could hold nothing, not even the smallest scrap of evidence, to help shed light on the Children of the Undying Fire. Ridiculous yet somehow typical. Zuko's luck had always been bad.

"You think that everything was destroyed in that fire," Zuko concluded in a dull voice.

"Most likely."

There was an unspoken "but" attached to the sentence. Zuko waited for his uncle to elaborate, but Iroh said nothing. Instead, a distant gleam entered his eyes and he stroked his beard in a contemplative manner. It was obvious that his mind was elsewhere, thinking of thoughts to which only he was privy. Zuko resisted the urge to sigh in exasperation. He hated it when his uncle went all cryptic.

"Uncle," Zuko prompted.

"It bothers me," Iroh admitted. "No matter how you look at it, the fact that fire healing exists means that one of these texts on firebending should have contained some kind of acknowledgement to the technique."

Zuko folded his arms across his chest. "But there is nothing."

"Indeed. There is something not right about this situation. I told you that the records I read in the palace archives had been poorly maintained and were barely legible. After coming here, I think that might have been intentional."

"What do you mean?"

"Someone wanted the Children of the Undying Fire to be forgotten." Iroh met his eyes grimly. "The palace archive is a place that few know about, let alone can access. It is home to the Fire Nation's secret history—every dark deed and buried truth—yet the scrolls stored about the Children of the Undying Fire had seemed incomplete when compared to the others. It wouldn't be a stretch to suppose that those records, perhaps even others, have been sabotaged to destroy any solid trace to the benders."

Zuko released a breath. "But why? What's so bad about fire healing? Why would someone go to such lengths?"

Iroh shook his head. "I don't know. However, it worries me that this tampering has reached even Wan Shi Tong's library."

Zuko's gaze shifted to the shelves brimming with books and scrolls. He felt helpless. There was so much information being stored in the library. Information gathered from all over the world. It seemed a cruel blow that none of it was of any use to him, especially if it was true that the only reason for why he had found nothing was because someone had tried to erase all of the evidence. His stomach twisted in unease as he remembered what Wan Shi Tong had said.

"I thought the humans had destroyed your kind."

Not one nation, as his uncle had inferred, but humans as a whole. It was an awful, sickening possibility. If Wan Shi Tong was to be believed, the world had feared and despised fire healers so much that they had committed mass genocide to get rid of them. True, there was no saying whether all of the nations had actually participated in the killing, but it sounded like no one had stepped in to stop the slaughter either.

Just like with the Air Nomads, a small voice whispered in his mind.

Zuko bowed his head. Emotions too tangled to unravel pricked his heart like a caress of thorns. It was his great-grandfather who had ordered all of the Air Nomads to be hunted and killed; the rest of the world had just turned a blind eye. Until recently, Zuko had even believed in the propaganda that had justified the genocide. Sozin had been a wise leader, just doing what he had to in order to protect his people from the threat of the airbender army and an Avatar who, it was claimed, was being raised to destroy the Fire Nation. It was an "us or them" justification that had been engrained into Zuko's mind through countless lessons.

And it was all lies.

No one who had got to know Aang would believe that the monks had raised the boy to be a weapon for the Air Nomads. Aang could be thoughtless, erratic, and a complete idiot at times, but there was no real viciousness in him. Zuko could admit that now. The devastation caused to the Fire Nation at the North Pole had been a rare moment of violence, birthed from desperation and grief. It was true that Zuko had not been able to understand as much then, consumed by his own distress after watching the navy get obliterated by a glowing monster. He understood now.

The Fire Nation had destroyed the Air Nomads. Aang had probably assumed the same thing was going to happen to the Northern Water Tribe. An unbiased part of Zuko could even acknowledge that something like that might have happened had Zhao and the navy not been stopped. The people of the Fire Nation had always been good at following orders.

And it was a Fire Lord who had sworn an oath to destroy the Children of the Undying Fire.

Zuko's hands trembled. There was a part of him—the part who had knelt on a stone arena and tearfully proclaimed that he was his father's loyal son—who still yearned to cling to the justifications that had helped him view the world in black and white throughout his childhood. The Fire Nation was home. The Fire Lords were supposed to be obeyed without question, for they were the best and wisest of the country, chosen by Agni himself to govern. But Zuko's faith had been shattered. It had cracked and been chipped away by a stupid kid who offered shy smiles and friendship instead of threats.

It had burned with the fire that had consumed his memories and untethered him from the engrained loyalty that had blinded his eyes.

Now, standing in Wan Shi Tong's library, Zuko felt the very foundations upon which he had built his faith crumble. He was one of the Children of the Undying Fire. His kind had been hunted and killed just like the Air Nomads. What was the justification? Was it just another lie fabricated by one of his royal predecessors, twisted through propaganda to appear as an unfortunate necessity? He had to know the truth. He had to know why the simple fact that he could use his bending to heal was such a crime in the sight of the world, even to the point where people had intentionally tampered with historical records to erase any evidence of the healers.

Zuko clenched his hands into fists. "I'm going to talk to Wan Shi Tong."

Maybe the books couldn't help him, but the over-grown owl definitely knew something about the Children of the Undying Fire. His uncle must have seen his determination, because he didn't even blink at the announcement. He just nodded and told Zuko that they would have to be careful. Wan Shi Tong was not a benign spirit.

"I know," Zuko said grimly, "but this could be my only chance to get information about my healing abilities."

Iroh gripped him by the shoulder. "Then let us make haste."

The two of them made their way through the web of rooms and stone archways, seeking out the spirit who guarded the library. It was like walking through a maze. The avian faces that had been carved into the mosaic tiles seemed to watch their progress, as if Wan Shi Tong's eyes were following their every move. Mocking. Uncaring. The stone owls watched, but there was no sign of the real spirit. Zuko's blood boiled. He knew that Wan Shi Tong was aware of their presence and their desires.

He stopped on the bridge where they had first arrived, jaw clenched and his eyes narrowed. "Wan Shi Tong!" he yelled, voice echoing off the walls. "Show yourself!"

Iroh groaned and pressed his palm against his forehead. "Nephew, you cannot order a spirit around. Especially not one like Wan Shi Tong."

Zuko didn't care. He was sick of being ignored and treated like nothing more than a source of amusement. "Wan Shi Tong!" he called again, turning in each direction in an attempt to get a glimpse of the owl.

That was when the walls started shaking.

Zuko stumbled on the bridge, almost losing his footing. Sand shook down through the cracks in the walls and ceiling, gathering intensity by the second until it was as if grainy waterfalls had burst forth from every corner of the room. Pillars trembled and the stone under their feet seemed to heave and groan. Zuko's heart quickened in his chest. Had his shouting awakened the spirit's wrath?

"W-what's happening?" he stammered.

Iroh pushed him towards the rope that led back to the desert. "We have to get out of here."

"But—"

"The library is being destroyed!" Iroh exclaimed, and gave him another push. "No information is worth your life! We have to get out while we can!"

Zuko hesitated. He desperately wanted that information about the Children of the Undying Fire. Plus, Aang and the others were still inside. Then he heard another voice: a girl shouting in panic that the library was sinking. It was Toph, the blind girl who had chosen to stay outside with the sandbenders. For a moment, it almost seemed like the shaking slowed, but then there were more shouts. Too many. Too violent.

Iroh's eyes narrowed. "We need to get to the surface. The young earthbender is in trouble."

Zuko knew that his uncle was right, but he still hesitated. He needed that information. If there was any chance to learn the truth about his healing abilities, he had to take it. "Go," he told his uncle. "I'll be right behind you."

"Zuko—"

"I won't let myself get trapped in here," he said with a ghost of his cocky smile. "I'll be quick. Besides, someone has to make sure the others get out safely."

Iroh didn't look happy at leaving, but then they heard what sounded like an air bison groaning in pain. Toph screamed something and the building started shaking again in earnest, only to slow a few seconds later. Iroh glanced up at the window that led outside in worry. Whatever was happening out there, it sounded bad.

"Go," Zuko repeated. "I swear I'll follow you."

Iroh pulled him into a hug that crushed his ribs, entreating him in a low voice to be careful. Then Iroh's arms were gone and the old man was clambering up the rope to join the earthbender outside. Zuko turned away from his uncle's retreating figure and hurried across the bridge. Sand continued to fall, coating the pathway and getting in his hair. No time to worry about that now. He had to be fast.

"Wan Shi Tong!" Zuko yelled, running through the maze-like corridors and rooms. "Where are you?"

He rounded a corner and collided with Katara, almost tripping over her legs as he got tangled with her in a bruising collision of chins and elbows. They both gasped and clutched at each other to steady themselves. Momo made an indignant sound and flew off her shoulder to find a safer perch.

"What happened?" he demanded. "Where are the others?"

"No time for that," Katara said, grabbing him by the arm and pulling her with him. "Just run!"

Zuko glanced over his shoulder to see Wan Shi Tong speeding towards them like a thing from a nightmare, almost oozing feathers as his size seemed to increase, filling up the space to block their escape. Everything about the owl's expression screamed cold fury, but Zuko had never been one to give up. He had to get that information.

"Wait!" He slipped free of Katara's grip and held out his hands towards the owl in an appeasing gesture. "Please, I just need to know the truth. I swear I'll leave this library and never return, but I just need to know. Who are the Children of the Undying Fire? Why did that Fire Lord swear an oath to destroy them?"

Wan Shi Tong laughed. "What does it matter? None of you will be leaving today."

"But—"

The owl lunged. Slender fingers latched around Zuko's wrist and he found himself being dragged behind the cover of a bookshelf as a sharpened beak hit the spot where he had just been standing.

"Are you crazy?" Katara hissed. "Why are you trying to talk to him? Wan Shi Tong wants to kill us!"

"I had to try. He might be the only one who can tell me anything about my healing abilities."

"Well, I don't think he's in a talkative mood!"

Zuko opened his mouth to respond, but then a feather drifted past his face and he instead grabbed her by her arms, pulling her up against his chest. A second later they were moving through the air in a dive-like motion, just missing being shredded by the owl's talons. Katara met Zuko's gaze in wide-eyed fear as they rolled to a stop. That had been too close.

"I think we should run now," she said.

"Agreed."

They both clambered to their feet and started sprinting towards the main bridge. Zuko's bending was useless, but he had his swords. He unsheathed them just in case while Katara called for Momo. The lemur appeared a second later, looking frazzled and with his green eyes rounder than ever.

"Where are Aang and Sokka?" Zuko asked as he and Katara ran side by side.

"Probably still in the planetarium," she panted. "I told them to hurry, but—"

Her words turned into an alarmed cry. Wan Shi Tong appeared before them, massive wings spread wide. Katara lashed out at the owl with a water whip, not even checking to see if the attack connected before she tugged on Zuko's wrist, urging him down a side corridor. He followed her without resistance, Momo gliding overhead. For now, there was no sound of pursuit.

"Think we lost him?" she asked.

"Don't know." He paused when he noticed the sleek-furred animal staring at them from where it sat in the middle of the corridor. He'd never seen a fox before—most animals were crossbreeds—but somehow he knew that the creature before him was indeed a fox. Pure and simple. "Is that—"

"One of the Knowledge Seekers," Katara said. "Yes. One of them helped us find the planetarium before. I think they somehow understand what it is we hope to look for in the library."

Zuko frowned. "There's something dangling from its mouth."

Katara made an anxious sound. She muttered something about how this wasn't the time to be stopping to chat to animals, but he wasn't listening. The Knowledge Seeker was carrying a scroll in its mouth: one that looked a little charred, as if it had been caught in a fire once. His heart pounded against his ribs. Could it be?

He sheathed his swords and knelt in front of the fox, meeting its ageless eyes. Intelligence. Knowledge. He sensed that this strange creature would understand him if he asked for what it carried, but there was no need. The Knowledge Seeker just stared at him and released the scroll into his outstretched hand before darting off in the other direction. The last thing Zuko saw of the fox was its bushy tail disappearing into the falling streams of sand.

Katara came to stand next to him. "What did it give you?"

Zuko tightened his hand around the scroll. "Hopefully, the truth."

Something rustled behind them. Feathers. Zuko tensed and grabbed her arm with his free hand, forcing her to run alongside him. Momo screeched in agitation, flying ahead of them like a white arrow. Soon, they were sprinting through the stone archway and onto the bridge where the rope still dangled.

"Climb!" Zuko ordered, tucking the scroll into his tunic and unsheathing his blades.

"You go first!" Katara responded, taking up a bending stance. "I'm not leaving my brother and Aang!"

Zuko didn't get the chance to argue. Wan Shi Tong had just burst forth through the archway, stone crumbling around him in broken shards. The owl took to the air, eyeing the two benders like a predator cornering its prey.

"Your swords and bending are useless against me," Wan Shi Tong said in his cold, ancient voice.

Something whistled overhead. Zuko glanced up to see Aang and Sokka fly past on the Avatar's glider. Sokka let go of Aang and raised the book he'd been clutching, using the force of gravity and his own strength to hit the owl with a hard blow to the head. Still in motion, Sokka sprang off Wan Shi Tong and landed on the bridge as the spirit wavered and plummeted towards the inky darkness below.

Katara beamed at her brother, but there was no time for happy reunions. The library was still shaking and getting steadily more buried with sand. The four clambered up the rope, Momo in tow, and escaped out the window. The sight that met their eyes had all of them gasping in unison.

"Those bastards!" Sokka growled, dropping to the ground and pulling out his boomerang.

There were sandbenders everywhere. Flashes of orange alerted Zuko to his uncle's presence. The old man was standing with his back to the bison and tower, cutting through the ranks of sandbenders with giant bursts of fire. Two of the desert nomads were not far from him, sending up walls of sand and trying to keep the other nomads and the ropes they wielded at bay. Zuko didn't spot Toph anywhere. Then he noticed she was standing directly in front of the sinking tower, feet dug into the ground and her arms raised.

"Toph!" Aang shouted, running up to her. "What's going on?"

She tilted her head in their direction. The sound of their voices must have reassured her because she abruptly lowered her arms as if she had been holding the weight of the world in her palms and could not carry it any longer. The tip of the spire vanished into the sand a second later.

Toph dusted her hands off and turned to face them. "You guys took your time," she said, blowing her fringe out of her face with a puff of breath.

Katara's eyes widened. "Were you the one stopping the library from sinking?"

Toph nodded. "Though the moment I was distracted with trying to keep you all from being crushed, more sand-sailers arrived and those sandbenders started attacking." She jerked her thumb over her shoulder. "Lucky the old man came to help our friendly koala-sheep."

Zuko glanced at where his uncle and two of their guides were still fighting off the sandbenders to keep them away from the bison. Without a second thought, he unsheathed his blades and ran to help, weaving his way through the nomads like a snake, striking and parrying and slicing through exposed limbs in a blur of twin blades. Dimly, he was aware of Aang and the others joining him. The combined power of their attack was too much for the sandbenders, especially when Aang learnt that their target had been Appa.

"You tried to steal Appa?" Aang yelled, magnifying his voice with the power of his bending.

There was no hope for the rogue sandbenders after that. Aang unleashed a storm of winds that turned their bending against them. Sand blinded and lashed at the men like tiny blades. Even Zuko and the others had to fall back to avoid getting caught up in the maelstrom. Still, Aang's rage had the desired effect. The sandbenders scrambled for their sand-sailers and retreated as fast as their bending could power the sails.

"Should we really just let them go?" Zuko asked, lowering his swords.

One of the sandbenders who had not turned against them stepped forward. Zuko thought his name was Kumo. "They won't come back," he observed. "You've demonstrated your strength today and Gashuin will be afraid that news of this will reach his father. He'll be too busy trying to come up with an excuse for why he called in members of the Hami tribe to help him steal what turned out to be the Avatar's bison."

Zuko frowned and stared back at the retreating sandbenders, watching the sails disappear over the dunes like white wings fading into the sunset. He hated to think what would have happened had his uncle not been there to help. Aang must have felt the same, for he suddenly threw himself at the bison.

"You're safe!" Aang said, pressing his face into the shaggy fur and hugging as much of Appa as he could. "No one is going to take you away. I won't let them."

"And aren't we all aware of it," Sokka said dryly. "Your little whirlwind trick got us as well, you know. I swear I have sand in places that I didn't even know existed."

Katara scrunched her nose. "Too much information, Sokka."

"Way too much information," Zuko agreed.

Aang pulled his arms away from Appa and stared at them a bit sheepishly. "Sorry. I just got so mad when I heard those guys had been trying to steal Appa."

"Yeah, we noticed," Toph deadpanned. Her hair and clothes were smothered in grainy specks.

Kumo let out a light chuckle. "It was certainly an impressive display. If Gashuin had known you were capable of that, let alone were friends with such powerful warriors, I doubt he would have tried to carry out his plan."

Iroh smiled at Kumo and the other sandbender. "Ah, but you were both a great help as well. It is thanks to your efforts that Master Toph was able to focus on keeping the library from sinking and that our furry friend is still with us."

Kumo held up a hand. "Please, you don't owe us any gratitude. We were hired to be your guides. The desert is a rough and unforgiving place, but that is no excuse for Gashuin and Fen's betrayal. I hope you won't judge all of us sandbenders by their behaviour."

Aang's mouth split into a wide grin. "Of course not. You helped us save Appa."

"That's right," Katara said. "We would never think badly of you."

Zuko said nothing. He recalled the argument he'd had with his uncle and Aang about whether they could trust the sandbenders. A part of him wanted to say I told you so, since they had indeed been betrayed, but then Kumo and that quiet guy had not turned against them. The two men had even fought against their own people, choosing the honourable course of action over loyalty to kinship. It was just another reminder that the world could not be separated into black and white, that sometimes being of the same nation or kin wasn't enough.

"Appearances can be deceiving. Wolfbats can appear as koala-sheep and koala-sheep can appear as wolfbats. What matters is that we must learn to discern the truth for ourselves."

Zuko thought he understood now. It was the reason his faith in the infallibility of his nation and family had started crumbling in the first place. People who were supposed to be his enemies had tried to be his friend and those who should have cared for him had hurt him instead. The world had become so messed up. All he could do was try to separate the lies from the truth in order to stay sane.

To survive.

His fingers curled around the scroll tucked inside the folds of his tunic. Well, at least now he could perhaps shed some light on what happened to the Children of the Undying Fire. He couldn't wait to find out what was written on the scroll. In fact, the moment the group all piled back on Appa and started following Kumo's sand-sailer to leave the desert, Zuko pulled out the rolled up parchment. Very carefully, he unfurled it to reveal several pages. His eyes widened as he realised it was an account written from before the war. The author was a scholar from Ba Sing Se named Shang. Most of the beginning was completely illegible, damaged from the fire that had almost consumed the scroll. Zuko started reading from where he could:

I watched the child place his hands on his mother's wound. His eyes glowed pale gold and I felt the warmth of life spark from his hands. The mother was miraculously able to walk again, but the child died not long after. No one would explain why. No one would tell me anything. The whole family acted as if nothing had happened. I do not understand. It's obvious to me that the young firebender healed that woman. I must research further so—

More fire damage. More faded words.

I think I have found the answer. It took a long time to get hold of the information, but it seems there was once a rare breed of firebenders who lived within the Fire Nation. The people called them the Children of the Undying Fire. They were marked by their pale gold eyes, just like that child I saw, though it seems they had high mortality rates. Perhaps this would explain the label of the benders being 'Children'. Few seemed to survive to adulthood. It is—

Zuko made a frustrated sound as the words once more became impossible to read. The parchment was so damaged.

"Is that the scroll the fox gave you?" Katara asked, leaning over him to peer at the page in interest.

Zuko grunted in affirmation.

Her brow creased. "How can you even read this?" She traced her finger along the page. "I have tried to learn more about the fire healers," she said slowly, struggling to connect the scorched words. "It is proving difficult. They are as old as the fabled Sun Warriors, yet they are buried in even deeper secrecy. I fear that I am being watched. My quest for truth has led me here, but ..." She sighed and shook her head. "That's all I can make out."

Iroh perked up and moved closer to the two. "Let me see."

Zuko handed the scroll over without a word. Iroh scanned the pages. With every sentence he strung together, the frown deepened on his face.

"It seems this Shang was indeed being watched," Iroh observed. "Look at what he writes near the end."

Zuko accepted the charred page. "My time is running out," he read aloud. "They are coming to silence me. All I can offer is this record and a name: Princess Shu—" Zuko squinted at the characters, but could not make out the rest of the name. He frowned and kept reading. "Somehow, I know it all begins with her. I wish I had the chance to uncover the full truth, though I fear I will be dead by the time the sun rises. I cannot say whether it would be wise for anyone to follow in my footsteps. The pale-eyed ones are dangerous, the Fire Lord is even more so. Perhaps it is true that some secrets are best left buried."

Those were the last legible lines.

Zuko closed his fingers around the scroll, bunching the papers in his fist. For a moment no one spoke. Zuko didn't even know what to think. Instead of answers, the account had only posed more questions. Who was this princess? Who were the people who had decided to silence the scholar? Somehow, Zuko had to figure it out. The question was where to begin.

"Keep that scroll safe," Iroh advised. "I'll read over it again later and see if I can decipher anything else."

Zuko nodded and tucked the rolled up papers back inside his tunic. It was all he could do until they found a new lead. That was when a thought struck him. Shang had mentioned that the Children of the Undying Fire were marked by their pale gold eyes. It was almost identical to what Shizue, his mother's lady-in-waiting, had said all of those years ago. The words were like a dream now, drifting in a space that had no ties to any set image, but he still remembered them clearly.

"He has the eyes, Princess Ursa."

Zuko's mother had known that he had the potential to be a fire healer, as had her lady-in-waiting. It was entirely possible that the two women had let slip other information. With his memories still incomplete, Zuko had no way of knowing if he could assemble a lead from the scraps of conversations he had overhead as a child. He would have to retrieve all of his memories somehow. It was the only way to know for certain, even if his chest tightened at the thought. His past hurt him, but he could not keep running. Not if he wanted to move forward. Not if he wanted to discover the truth.

He turned to Katara, who sat next to him. She tilted her head, gazing back at him in question. He could see the tension in her shoulders, the pinched look of a person trying to appear unaffected, but not quite able to hide her discomfort. No doubt she was wondering why he was staring at her so intently all of a sudden. Zuko took a deep breath. It was now or never.

"My uncle says you can heal sicknesses of the mind," he said, holding her gaze. "Will you help me retrieve my memories?"