I swear, one what if scenario pops into my head and before I know it I'm planning out a whole story. I've got plans for a number of chapters, but I'm unsure exactly where this is going to end up and how long it's going to take.

The sun was low in the sky. A lone boy dressed in Air Nomad robes was sat on a flying bison heading west. The bison gave a low groan and the boy patted its head.

"Don't worry, Appa," the boy, an Airbender named Aang, said gently, "It shouldn't be too far. In fact," the boy squinted into the distance and grinned, "I think it's right there! Come on buddy, yip yip!"

The bison flicked its tail, speeding up at the excitement in Aang's voice. A spit of land could just be seen, growing larger as they got closer to it. It was belching smoke from a high volcano and thin streams of lava were trailing down the side and into the sea. The island was in the shape of a crescent moon and Aang's face brightened further.

"This is it, Appa!" Aang said, almost bouncing with joy, "I bet we'll find loads of stuff here!"

Appa gave a grunt and settled down to sleep as soon as they landed. Aang paused, but decided that the island couldn't wait any longer and set off exploring. He ran over to the lava streams and threw some pebbles in to watch them melt in the liquid rock. Growing bored, Aang then moved on to examine the remains of some sort of building. Unfortunately he didn't find anything of interest before a tremor knocked him off his feet.

"Hello?" Aang called out, picking himself up, "Anyone there? Earthbenders?"

There was silence. Aang shrugged and made his way back to Appa. Exploring was fun, but it'd have to wait for tomorrow so he actually could see what he was poking at. He found the bison asleep just as the sun set. Curling up on Appa's tail, Aang gave a yawn and soon dozed off, dreaming of Fire Nation treasures.

Aang woke with a start. The sun was nowhere to be seen and moon was still bright in the sky. It wasn't the only bright thing however. Chunks of flaming rock were falling from the sky. Aang watched them for a few moments before his mind slipped into gear. He looked around Appa to see his suspicions confirmed.

The volcano was erupting.

"Come on, Appa," Aang yelled, Airbending himself onto the bison's head, "Yip yip! Hurry up!"

Appa groaned in complaint, but heeded his young master's orders. Not a moment too soon. A large boulder landed where Appa had been seconds before. Aang squinted at it, there was something strange about the rock that he couldn't quite put his finger on. He steered Appa as close as he dared.

The boulder had sustained several long cracks on its impact. As Aang watched the cracks deepened and a brilliant blue light poured from them. The boulder finally shattered and much to Aang's amazement there was someone sat inside of it. A boy, older than Aang, slowly stood up, the blue light spilling from his eyes. The light faded and the boy fell, sprawling over the smoking chunks of the rock he had emerged from.

There was a loud explosion. Aang watched the volcano spew another set of fiery projectiles from its smoking maw. Without stopping to think, the young Airbender steered Appa down to the other boy. Aang quickly pulled the other boy into Appa's saddle and took off again.

"There's another island nearby," Aang told Appa, "We'll get a good night's sleep there."

Appa gave a groan and flicked his tail to gain height. Aang glanced over at the unconscious boy in the saddle.

"I hope he's alright," Aang said, biting his lip.

Appa grunted.

"You're right," Aang said, turning his gaze back to searching for the island, "There's no use worrying about it now. The best thing we can do is make sure he's got somewhere safe to recover." Aang patted his bison's head fondly, "What would I do without you, buddy?"

All thoughts of a good night's sleep vanished from Aang's mind as the stranger coughed and sat up the moment they landed on a nearby island beach. Aang moved into the saddle too, waiting for the other boy to wake up properly. Appa yawned and settled down to go to sleep again.

"Who are you?" Aang jumped at the sharp tone the other boy used, "Where have you taken me?"

"I'm Aang," Aang said, "And I'm not sure. We got you off that other island, the volcano was erupting!"

The boy scowled and leapt off the bison's saddle. Aang followed, Airbending his way easily. The other boy was picking up some bits of driftwood and stacking them in a small pile. Aang did his best to help.

"What's your name?" Aang asked, placing a bit of wood on the pile.

"Zuko," the other boy replied, restacking Aang's bit.

"Nice to meet you, Zuko," Aang said cheerfully. Then something dawned on him, "You're not Water Tribe, are you?"

"Hardly," Zuko snorted.

Aang relaxed. Zuko had stopped picking up the wood, so Aang joined him in sitting by the pile. Zuko punched toward the wood and a small blast of flame flew out of his fist and lit the driftwood on fire.

"You're a Firebender?" Aang gasped, his eyes wide.

Zuko didn't say anything. Now that he was lit up, Aang finally took a good look at his new friend. Zuko's hair reached his eyes, but didn't completely cover up a large burn scar that covered the left side of his face. His left eye was set in a permanent glare from it. Zuko was wearing red clothes – something Aang had only ever seen in pictures before.

"But Firebenders are extinct!" Aang said, "No one's seen any for a hundred years!"

"That's impossible," Zuko snapped, "What about the Fire Lord?"

"There hasn't been a Fire Lord for that long either," Aang said hesitantly, "The Fire Nation were wiped out."

"You're lying," Zuko said angrily.

"I'm not," Aang insisted.

There was a long silence.

"We'll go to the capital tomorrow," Zuko said firmly, "We'll find my father and prove that the Fire Nation are still around."

"Ok," said Aang, "Appa can take us, can't you buddy?" there was no reply from Appa. Aang grinned sheepishly, "He's sleeping, it's been a hectic night."

"That's a flying bison," Zuko said, having only just properly noticed Appa.

"Yeah," Aang said happily, "He's been with me ever since he was only this big." Aang stretched his hands about three feet apart.

"It's hard to imagine he was ever that small," Zuko said, glancing at the fully grown bison again. "We should get some rest. It's a long way to the capital."

Aang nodded his agreement and curled up on Appa's tail as usual. Zuko lay down by the fire, watching the wood burn down slowly.

Sokka was bored.

He'd plotted and re-plotted their course for the next few weeks. He was up to date on all of the Water Tribe's movements – not that anything was happening near him. Katara and Paku were taking up the deck to Waterbend, so Sokka couldn't train with his boomerang or sword.

There had never been quite such a dull moment on his trip so far. He'd spent one year out of two already searching the world for the Avatar. Not for the first time Sokka cursed the coming of age tradition that his father had pushed him into. Two years hunting someone that nobody had seen for a hundred years. It was stupid.

Of course he could always go on deck and – provided he avoided the Waterbenders – watch the Fire Nation islands pass by. That would have been more interesting if he hadn't already seen them before. Rich, green, bountiful islands that would have been a great place to settle down if it weren't for the volcanoes. Anytime the Water Tribe set up villages there would be an eruption within the year. It was like the Fire Nation was still fighting back, even after all this time.

Not that it did much good, the only Fire Nation person alive was the Avatar, and to be honest, Sokka doubted his existence.

Sokka stood up and stretched. Even with the risk of being hit by a sheet of water, being on deck was going to be more interesting than being sat down here. Sokka ambled his way through the corridors of his ship and up onto the deck.

Katara, Sokka's younger sister, was stood in the middle of the deck with several tentacles of water forming a protective ring around her. Octopus form, Sokka remembered seeing it before. Master Paku was drawing water up and over the side and pelting icicles at Katara, who used the tentacles to block or grab the icicles out of the air. Neither master nor student paid any attention to Sokka as he made his way to the side of the ship.

"Hey!" Sokka yelled over, startling Katara, "How much longer are you going to be?"

Both Katara and Paku scowled heavily at the young warrior. Sokka gave a friendly grin and unsheathed his sword.

"As long as we want to be," Katara shot back.

"It's my ship," Sokka pointed out, "And I want to train now. You've been at this for hours."

"It's not your ship," Katara said, "It's dad's. So it's just as much mine as yours. I need to master this form."

"Your brother raises a good point," Paku interrupted the sibling's argument. Katara scowled as he continued, "It may be best to take a break and start again later. The way to mastery is not through exhausting yourself."

Katara raised her arms then pushed her hands to one side, streaming the water neatly into the ocean. She gave Paku a short bow and stormed off below decks, no doubt taking her frustrations out on tonight's dinner. Paku watched Sokka as he began stepping through his swordfighting forms.

"Your sister chose to come on this journey with you," Paku reminded the boy, "You shouldn't aggravate her... no matter how bored you may be."

"She only came because it was the only way she'd learn any real Waterbending from you," Sokka said, "And so no one can say she didn't do the 'finding the Avatar' task as well as any boy would've."

Paku gave a hum of agreement.

"There'll be no keeping her out of the fighting once we get back," Sokka said, practising a few thrusts, "She'll want to be on the front lines to help people now she can actually fight."

"Neither your sister nor you will be involved in any fighting if I have anything to say on the matter," Paku said sharply.

"Our dad's the chief of the Southern Water Tribe," said Sokka, "We've got to help in this war in any way we can."

Paku stayed silent, frowning at the young warrior.

"Enjoying yourself?" Aang called over to Zuko.

The Firebender was clutching onto the raised edge of Appa's saddle tightly, looking over the side in wonder. Aang climbed across until he was sat next to Zuko.

"I've never flown before," Zuko admitted, "It's amazing, just like I imagined riding a dragon would be."

Aang's face fell slightly, but Zuko didn't notice. The Airbender shook his head and put on his bright smile again.

"I can fly without Appa," Aang said, grabbing his glider, "Watch!"

He leapt off Appa's saddle, enjoying the rush of air.

"Aang!"

Aang opened his glider and flew up until he was level with Appa. Zuko had a look of relief on his face.

"See?" Aang called.

Zuko nodded. Aang flew over Appa's saddle, shut his glider and landed next to Zuko again, giving the Firebender a big grin.

"So those tattoos are what I think?" Zuko asked, "You're an Airbending master?"

"That's right," Aang said proudly, patting his arrow.

"But you're just a kid," Zuko said in disbelief.

"Guess I'm just lucky," Aang said, "Are you a Firebending master?"

"No," Zuko said immediately, then just as quickly, "Yes. Maybe. I'm considered to be pretty good, but I've still got some things to learn before I can be considered one of the best in the world."

"Did you ever hear about the Avatar?" Aang asked, "Legend says he could bend all four elements."

"I've heard of him," Zuko said, not matching Aang's excitement one bit.

"Can you imagine how much fun that would be?" Aang said enthusiastically, "It's great being able to Airbend, but think about all the things you could do with Earthbending or Firebending, or even Waterbending!"

"The Avatar has to keep the world in balance," Zuko said warningly.

"I guess that side wouldn't be much fun," Aang pulled a face, "But I'd still like it."

"That makes one of us," Zuko muttered too quietly for Aang to hear.

Sokka's blade sliced through a set of icicles Paku shot at him. So far Sokka hadn't missed a single one, but he was tiring. He tightened his grip on his sword hilt and nodded to Paku to indicate that he was ready for the next wave. Paku pulled a stream of water up from the ocean, then let it drop, his attention caught by something in the sky.

Sokka looked up and could just make out the shape of a flying bison against the cloud-ridden sky. It was heading west and it was going quite fast. Sokka sheathed his sword, but his confident grin faltered when he caught sight of the look on Paku's face.

"It'll be good for the crew," Sokka insisted.

"The Air Nomads are peaceful," Paku stressed the word, "There will be no more than five of them on a lone bison."

"They've got a destination in mind," Sokka said, "They could know about the Avatar."

"The Avatar hasn't been seen for over one hundred years," Paku said sternly.

"It's good practise," said Sokka, "I'm going stir crazy and Katara will want to come along too."

"You know how much I dislike you bringing your sister into these skirmishes," Paku said.

"It's just a few Airbenders," Sokka said, "We're going after them. Helmsman!" Sokka raised his voice, "Follow the bison."

There was a flurry of activity as the crew set about giving chase. Paku sighed at Sokka's stubbornness. It was beginning to look like a long day.

It was late afternoon by the time Zuko spotted the Fire Nation capital. Aang was impressed at the size of the place. He hurried Appa up, wanting to get there even faster.

"Is it all inside that volcano?" Aang asked the older boy.

"The city is," Zuko replied, "There's guard towers at the port and we should be passing over the Great Gates of Azulon soon."

"Wow," Aang said, his eyes wide open, trying not to miss a thing.

"When invaders would come by sea the gates would rise out of the water and catch fire," Zuko said, "My uncle took me to see them once."

"Wow," Aang repeated.

He urged Appa lower, anxious to see the landmarks Zuko spoke of. However, Zuko was now frowning.

"They should be right there," Zuko said slowly, "Maybe I misjudged the distance and we've already passed them."

"Yeah," Aang said quickly, realising that maybe the gates were gone for other reasons, "Maybe."

They were silent as Appa cleared the rest of the bay. The bison landed at the foot of the volcano and the boys clambered off. Aang stared up at the steep sides and the narrow winding path in disbelief.

"Why couldn't Appa just fly us up?"

"It'll be worth the climb," Zuko promised.

"Ok, be good buddy," Aang said, patting Appa.

The bison gave a low grunt and Aang and Zuko started to walk up the path. Aang noticed Zuko glancing at the guard towers more than once. Not knowing what to say, Aang let this part of their journey pass in silence too.

"We're here," Zuko's words jolted Aang out of his thoughts.

"Wow!" Aang said, yet again.

The Fire Nation capital looked amazing. The houses were all extravagant, laid out elegantly in the volcanic crater. A serene lake mirrored the crater edge in its still surface and the sprawling palace looked beautiful under the sun. It was red and gold and white and Aang had never seen anything like it. He glanced at Zuko and was surprised to see a heavy frown on his face. Then Aang realised what was wrong.

It was silent. The streets should have been filled with people going about their daily business, shopkeepers trying to sell their wares, children playing. There was nothing. The capital was empty. Zuko started down the path abruptly and Aang scrambled along behind him. The high crater walls cut off the sun and Aang shivered involuntarily. It felt like walking into a ghost town.

"Why were the Fire Nation wiped out?" Zuko suddenly asked.

"The Water Tribe attacked," Aang said quietly, "They managed to kill everyone in the Fire Nation. They set their sights on the Earth Kingdom next and they've been at war all this time."

"And the Air Nomads?" Zuko asked, staring straight ahead.

"They've left us alone, for now," Aang replied, "If there's one thing Airbenders are good at, it's avoiding fights."

"Just because Firebenders haven't been seen for one hundred years doesn't mean that they still aren't around," Zuko said, though his voice was far from confident, "I'm still here."

"Yeah," Aang said, "Hey, are we going to the palace?"

Zuko nodded and Aang's face lit up.

"You used to live in the palace?"Aang said, awed, "Wow, it must've been great living so close to the Fire Lord!"

Zuko gave another nod, putting all his focus into getting to his destination. Aang took his cue and fell silent again.

A shout woke Appa. He grumbled in annoyance, but forced himself awake when he realised what it was. Water Tribe. Appa quickly flew up and over the crater rim. There was no sign of his master or the boy that smelled of ash. Appa flew low until he found the perfect hiding spot. The large building in the middle of the crater would shield him from view. Appa could only hope that his boys would return soon.

It had always been quiet in the halls of the palace, but Zuko had never been in them while they were so empty. Normally by this point he would have run into someone, but, just like in the city outside, there was no one. Zuko didn't want to believe Aang's words about his people, but it was beginning to look like he didn't have a choice.

One hundred years.

It was such a long time ago. The walls of the royal palace were build for endurance, it would be many more years before they succumbed to the elements. Zuko almost wished they were weaker, as long as they were still standing it gave him hope for the Fire Lord's fate.

"Aren't you going in?" the young Airbender's voice startled Zuko.

Zuko found himself in front of the throne room, merely a dusty curtain separating him from the truth. The Airbender – Aang – was watching him curiously. Zuko took a steadying breath and pushed the curtain to one side. The two entered the large room and walked to the centre.

"Wow," Aang breathed, turning around as he walked to see everything.

"This is the throne room," Zuko told him, "The Fire Lord sits there," he pointed up at the dais, "And fire surrounds him."

"Wow," Aang repeated his favourite word.

It was too much. The walls felt like they were pressing in on Zuko. The Fire Lord was dead. There would be no other reason why the throne felt lifeless. His father, his sister, his uncle. Zuko fell to his knees, taking gasping breaths. They're all gone. He was alone.

"Zuko?"

Well, not completely alone.

"Zuko? Are you ok?"

Aang's hand patted him on the back. It was grounding. Zuko shakily got to his feet, glad of Aang's support.

"I really am the last Firebender," Zuko said quietly.

Aang gave him a hug. The younger boy looked like he didn't know what to say. Zuko didn't know what to think. They stayed there until Zuko got his breathing back under control. Aang released him slowly.

"I'm sorry about your people," Aang said solemnly.

"It's not your fault," Zuko said.

Suddenly about a dozen people dressed in blue burst into the throne room. All but one had some form of weapon in their hands, the last – the only girl – had taken what Zuko knew was a Waterbending stance. Zuko dropped into his Firebending stance without thought and Aang held his staff forward like a weapon. The Waterbender and a boy with a sword – both younger than Zuko, but older than Aang – were at the front.

"You're trapped," the boy said confidently, "Give up and we won't hurt you."

"We can outrun them if we get outside and on Appa," Aang whispered.

Zuko nodded his agreement.

"You had your chance," the boy said, tightening his grip on his sword, "Attack!"

The Water Tribe surged forward. Aang leapt off to one side, bringing his staff down as he landed and sending a fair few of the warriors flying with a gust of air. Zuko mirrored his leap, leaving the Water Tribe between the two, and executed a fiery kick that blasted another few soldiers away.

"He's a Firebender!" someone in the Water Tribe yelled.

"Katara!" the boy shouted at the Waterbender, "Take care of the Airbender. Everyone else, we're dealing with the Firebender."

The boy and Katara moved quickly, but the other warriors were staring at Zuko in surprise and awe. The Waterbender and Aang began to fight, Aang mostly avoiding the shards of ice she threw in his direction. Zuko focused on the sword wielding boy who was closing in on him.

"If you're a Firebender, then you're the Avatar," the boy said smugly, "I expected you to be older."

Zuko snarled and unleashed a volley of fire balls that forced the Water Tribe boy to duck behind a pillar. This seemed to snap the rest of the men out of their surprise and they rushed to his aid. Zuko was now outnumbered eight to one. He lashed out again, catching a few of the warriors with his fire. Then he was ducking and weaving to avoid being clobbered and slashed.

A cry of pain echoed through the chamber. Zuko looked up to see Aang being frozen to the floor by the Waterbender. Something snapped inside Zuko. The Water Tribe had taken away his people and he hadn't been there to stop them, he was not going to let anyone else be hurt.

Aang was cold. He tried to wiggle free, but the ice was unyielding. The Waterbender was looking pleased with herself as she stood over her foe. Then she was looking surprised, almost scared. The air in the room suddenly felt hot and dry. Aang twisted his head around to see the throne be surrounded with fire, just like Zuko described.

"Katara!"

The Water Tribe boy – the one that seemed to be in charge – yelled across the room. Aang twisted his head around again and gulped. There, with his eyes glowing brightly and flames dancing wildly around him, was Zuko. The ice holding Aang melted in seconds and he scrambled to his feet. The Waterbender ran across the room to be with the rest of her people.

Zuko's attention was focused on the Water Tribe. He brought his hands across his body and fire rushed toward his enemies. They scattered, diving behind the pillars that littered the throne room. Zuko's fire left huge scorch marks where it touched the stone. Zuko held his hands together in front of his chest, then punched upward, sending an enormous blast of fire into the ceiling. It exploded, leaving a hole to the sky. Zuko sent another gout of flame at the Water Tribe, keeping them cowering.

The light left Zuko's eyes and he slumped forward, landing on his hands and knees. The flames around the throne went out, leaving the room much darker. Aang rushed over to his friend and helped him to his feet. The Water Tribe were recovering and began to close in again. Aang opened his glider.

"Hold on," he told Zuko.

The Firebender had just enough presence of mind to do as Aang instructed and grabbed onto the back of the offered glider. Aang took a few steps as run up then launched himself into the air. Zuko's earlier display had heated the air significantly, which made it easier to fly up and out of the hole Zuko's bending had created.

Aang had just landed at the edge of the hole when a boomerang attached to a length of rope wrapped neatly around his ankles and pulled him back into the room. Aang yelped in surprise, but Zuko grabbed his wrist with one hand and shot a small amount of fire at the rope with the other. With the rope severed, Aang kicked his feet free and moved away from the hole.

"That was close," Aang panted.

"It's not over yet," Zuko warned, "Where's your bison?"

With a grin, Aang reached inside his clothes and retrieved a whistle in the shape of a bison. Zuko didn't look impressed, especially when Aang blew it and no noise emerged. Sure enough though, Appa flew up to them and landed on the roof.

"It's a bison whistle," Aang explained to a confused Zuko, "They can hear it, even if we can't."

Zuko nodded mutely. He clambered up Appa's tail and into the saddle while Aang leapt into his head.

"Yip yip," Aang said.

Appa flicked his huge tail and they were airborne.

Sokka and Katara ran through the maze of a palace, skidding to a halt once they reached the outdoors. Master Paku was waiting for them, his usual frown on his face.

"Has the bison left yet?" Sokka gasped, out of breath from the run.

"No," Paku replied, "He's there."

The siblings turned to see the sky bison fly overhead. Katara ran to the pots of water she insisted they bring with them on every trip.

"You should let them go," Paku said, moving over to the pots too.

"It's the Avatar," Katara said quickly, taking her stance and pulling the water into her command.

Paku's eyebrows rose and he stepped into place next to his student. Together they formed a few long ice spears and launched them toward the escaping bison. Before they hit their target a blast of fire was shot from the bison's back and melted the spears in mid air. The rest of the warriors who had went in with Katara and Sokka emerged from the palace.

"Everyone back to the boat," Sokka called, "We're making chase."

The warriors obeyed rapidly. Sokka caught up with Katara and Paku and walked with them.

"So you met the Avatar," Paku said, "The last Firebender. He overpowered you all?"

"He went into the Avatar state," Sokka said bitterly, "And he had an Airbending kid with him. Don't worry, we'll get him next time."

"I'm sorry, Master Paku," Katara said.

"Katara?" Paku asked.

"I used up all my water to pin the Airbender down," Katara said, "When the Avatar attacked I had none left. I'm sorry for failing you."

"Don't worry about it, Katara," Sokka said before Paku had the chance to say anything, "We'll make sure there's plenty of water around for you to get him next time."

Katara smiled at her brother and the two went on ahead, discussing what would happen next time they met the Avatar. Paku sighed, he was getting too old for this.

"So..." Aang said, "You're the Avatar?"

"Yes," Zuko replied shortly.

Aang made sure Appa was on course and climbed into the saddle to talk to Zuko properly.

"So you can bend all the elements?" Aang asked.

"No, not yet," Zuko said, "I'm only a Firebender right now."

"But you need to learn Airbending next, right?" Aang pushed, at Zuko's nod he grinned, "We can go to the Southern Air Temple. It's where I learnt all my Airbending, I bet the monks would teach you too."

"That makes sense," Zuko said.

"Great," Aang said excitedly, he leaned over the edge of the saddle, "Here that buddy? We're going home!"

Appa gave a growl of approval. Aang sat back up and his face fell when he saw Zuko hunched over, staring at his feet.

"Zuko..." Aang said, unsure what to say, "I'm sorry about the Fire Nation."

"There's nothing we can do about it," Zuko said firmly, "What I have to do now is learn all four elements and bring balance back into the world."

Aang moved over and sat next to Zuko. His eyes fell on Zuko's scar, but he decided that now wasn't the time.

"You can tell me about them," Aang offered, "The people you miss."

Zuko stayed silent. Aang didn't push the matter. They both watched the Fire Nation capital get smaller as Appa took them further and further away from it. It was going to be hard, but Aang was going to be there for his friend, no matter what.