Disclaimer: All rights belong to Nickelodeon, Bryan Konietzko, Michael Dante DiMartino, and all the men and women that created the A:TLA show, books, and comics. I take no credit, and I do not mean to break any copyright rules. This is simply a work of fiction made for enjoyment. No money is being made. The lyrics are from the song "Centuries" by Fall Out Boy

Rating: General Audiences. Warning: some scenes contain dark themes and minor violence

Author's Note: Hey everyone! I'm very excited to present my first A:TLA fanfiction. I've spent the last year working on this fic, so I hope you enjoy it! It's set in an AU where Katara is the Avatar. The fic follows very closely to the canon, and there are some chapters in which I used what happened in the show and simply adapted it to fit into my AU. That being said, there are a few differences, all of which are explained in the story.

This is a Zutara fic, and a lot of the plot revolves around their (complicated) relationship. There will be a lot of angst, but I promise that there's a happy ending. I have written and edited the entire story, and will update twice a week as possible. It is broken up into 5 books with sixteen chapters each, the books being like seasons and chapters being like episodes. The first few chapters are shorter, but I promise they get longer.

Comments are always appreciated! I will try to respond to them all, but if I don't, it's not because I don't want/appreciate them.

BOOK 1: The Last Waterbender

Water. Fire. Earth. Air.

Long ago, the four nations lived together in harmony. Then everything changed when the Fire Nation attacked.

Only the Avatar, the master of all four elements, could stop them. But when the world needed her most, she vanished.

A hundred years have passed and there is no sign of the Avatar.

Chapter 1 - The Girl in the Ice

Just one mistake

Is all it will take

We'll go down in history

-Centuries, Fall Out Boy

"Remember: breathing is the key to firebending," Iroh says. The older man is sitting on a stool on the deck of the large battleship, a cup of tea cradled in his hands. Steam rises from the surface, disappearing into his gray beard.

Zuko takes a deep breath before resuming his attack position. He steadies his stance and then exhales as he waves his arms and swings his legs around, jumping gracefully through the air before finally pushing a blast of fire out of his palms.

"Good, good. You are improving every day," Iroh says. He lifts the cup to his mouth and takes a long draught.

"Not enough," Zuko replies, staring distastefully down at his hands. "If I'm going to capture the Avatar, I must be stronger. He's a master of the four elements; I must be overwhelmingly powerful in order to even have a chance."

"You are one of the best Firebenders."

Zuko clenches his fist. "One of the best. After you, my father, and my little sister, of course." He glares at the water around them. "Not that it matters. We've been searching for two years without a hint of the Avatar. Wherever he is, he's not coming out until he wants to. I'm never going to find him. And I'm never going to restore my honor."

"You never lost your honor, Prince." Iroh sets his tea cup down. "Only in the eyes of your father."

"And in front of the entire Fire Nation." Zuko stares off the bow of the ship to the icebergs floating lazily in the water around them. Two years ago he'd been humiliated by his father in front of his people. Not only embarrassed, but banished. And the only way to regain his rightful place as heir to the throne is to bring back the Avatar - a person who mysteriously disappeared one hundred years ago.

Also the only person powerful enough to stop his father's conquest of the world.

A cold wind blows across the ship. Zuko holds his arms. "Remind me again why we're in the coldest place in the four tribes, Uncle."

"This is the only place we haven't searched yet." Iroh looks distastefully at his tea, which has already frozen in the mug.

"There's no one here. Just icebergs and water. Where are all the people?"

"The Southern Water Tribe used to live here, before your great grandfather Sozin destroyed them all. The last Avatar would have been from one of the Water Tribes, so your grandfather attacked them both. Only a handful of people survived the battles, none of them the right age to be the Avatar. But the Avatar never revealed himself or used his powers."

Zuko whirls around. "So you're saying the Avatar might have grown old and died in hiding? He could now be an Earth Kingdom toddler? I could be looking for years before the Avatar is old enough to reveal themselves!"

Iroh shrugs. "The previous Avatar could still be alive. He would be a little over one hundred years old, but it's very possible. Avatars can live to be quite old."

The young prince paces angrily across the deck. "I hope we finish searching soon. I'm freezing."

Iroh chuckles. "Then practice firebending some more. A good workout will get you warmed up in no time." He picks up his frozen saucer and melts his tea with a swirl of his finger.

Zuko resumes his stance and breathes deeply. He sees a large iceberg just off to the side of the ship. "Let's see how much damage I can do to that chunk of ice. Remind this wasteland why the Fire Nation is the most powerful."

He aims his hands, then runs through his attack motion, sending the largest fireball he can muster towards the iceberg.

It hits its target right in the center, connecting with an explosion of steam. Zuko smiles as partially melted snow chunks slide off the formation and splash into the sea.

"Good one," Iroh says approvingly. A few of the crewmen standing on deck nod in agreement.

"Think I'm ready for more complex moves yet, Uncle?"

His uncle chuckles. "Undoubtedly. But first we must find the nearest trading post and get more tea." He stares forlornly at his empty saucer. "I can't teach on an empty stomach, and this was the last of our tea."

Zuko glares at the man. His honor is at stake here, and his uncle is worried about tea? That's his priority?

"What about lightning?" Zuko asks. "You haven't taught me how to throw lightning yet."

Iroh's forehead crinkles. "Like I said - "

"Prince Zuko!" A crewman comes running towards the prince.

"What is it?" Zuko growls. "I'm busy."

"There's something out there," the crewman insists.

"Out where?"

"On that iceberg! The one you hit, sir."

Zuko snatches the binoculars out of the man's hand and raises them to his eyes, zooming in. "I don't see anything."

"Look to the left."

He follows the man's instructions. Sure enough, there's something lying on the ice. "It looks like...a person. Are they alive?"

"We don't know, sir. Shall we take a closer look?"

"Only a descendent of the Water Tribes would live in such conditions," Iroh observes. "Perhaps they know something about the day Sozin attacked."

"And have information on the Avatar." Zuko lets his lips stretch into a tight smile. This could be the break he needs. "You're right. Turn the ship around. We're going to speak to that person."

The crewman runs to the control room. Zuko continues looking through his binoculars. He's not letting a potential lead get out of sight.

Too much is at stake.

Katara feels her head spin. She wakes up with the cold sensation of snow around her and a distinct ache from her muscles, but she can't seem to move her body. Her eyelids feel heavy and welded shut.

How did she get here? She tries searching through her memories, but she's startled to find only darkness. She can't remember anything.

The shocking revelation is enough to jolt her body into action. She sits up suddenly, which only causes her head to spin faster. She swallows back the vomit that rises in her throat and just tries to focus on breathing.

Okay, she thinks. I can't remember anything. It's just temporary amnesia. I must have hit my head. Everything will come back to me soon.

She stands up and looks around. White and blue. Snow and water. This looks familiar. She must be near her home.

Home. A quick snatch of memory. She sees a hut carved out of the snow. A cluster of huts. A wall of ice in the background.

Good, she tells herself. You remember that your home is here. See, it's already coming back!

Then, Wait - where is here?

She glances down at her clothes. Blue-dyed wool with a white fur trim. Long sleeves, tunic, and trousers. Leather boots. She's dressed for cold weather. There's snow everywhere, but the sun is shining. So she must be in one of the poles.

Katara takes another deep breath. "Okay," she says aloud, hearing her voice for what feels like the first time. It's a sweet voice, but scratchy - as if she hasn't used it in a while. "Let's see what we remember. My name is Katara. I'm sixteen years old. I'm from here - here being one of the poles. I live in a tribe somewhere. Now, how did I get on this iceberg? And how do I get back home?"

She looks around. Nothing but sea and icebergs and a ship.

Wait. A ship?

She turns and uses her hand to cover the glare from the sun. A large, iron ship is heading her way, spouting smoke high into the sky.

"Someone's coming for me!" she says excitedly.

The ship doesn't look right, though. Another flash of memory - a canoe made of whale bone and animal hide and covered in wax to make it airtight. They were fast and easily maneuverable, especially good for traversing between icebergs. Not like this iron giant, which just plows straight through, cutting through them like a hot knife through butter.

No, this ship is not from her tribe. But maybe they'll help her find her people, whoever they are and wherever they may be.

She waves her hands at it, trying to draw attention to herself. The ship slowly comes to a halt, and men wearing pointy black and red uniforms throw an anchor over the side. A smaller boat is lowered down from the ship, filled with five men. At the sight of them, a flash of fear runs through her. She pushes it away, not understanding where the emotion is coming from.

Even if she should be wary of them, she's more scared of starving to death out on this iceberg.

Katara waits patiently for them to disembark. As they get closer, she can see four of the men wearing uniforms with disturbing masks. The fifth man walks in the middle of them. He wears not a uniform but expensive armor of red, gold, and black. His dark hair is pulled up in a queue. Whoever he is, he's important. Katara is starting to get a bad feeling about these people. Maybe starving on the iceberg isn't such a bad thing, after all.

When they are only a few paces away, the man in the middle holds up his hand. The others halt. He approaches her alone. For a moment they just stare at each other. She can't help but notice a horrible burn scar across the left side of his face. His left eye is barely visible under the pink scar tissue. Other than that, he looks so young - her own age, actually.

"Who are you?" he finally asks. "And what are you doing here? Where are the others?"

"I'm Katara." She bites her lip and looks away. "And I don't know what I'm doing here."

"What do you mean, you don't know?" His eyes narrow in what can only be described as suspicion.

"I just woke up here. I don't remember anything. I must have hit my head or something."

"You don't remember anything?"

"Well…" she swallows. "I remember that I'm from here. I live around here somehow, I think. But I don't know where exactly. I was actually kinda hoping you could help me."

She makes eye contact with him again, hoping she looks young and helpless enough.

"You're from the Water Tribe?" he asks.

"Yes. I think." She glances down at her outfit again. "If you could just take me to the nearest Water Tribe village and drop me off, I'm sure I'll find someone I recognize and they can help me home. Please? Otherwise I don't know what I'll do. I don't have any supplies or a boat."

The boy stares at her for another long minute. His expression is unreadable. Katara holds her breath. She has a feeling that something isn't right, but she doesn't know what exactly, so she pushes it away. There's nothing she can do right now except follow him.

"Alright. You can come with us." He turns and waves at his guards. They all start walking back to the boat. Katara jogs so she can catch up to the boy. His guards raise their weapons slightly, but she ignores them.

"Wait. You never told me your name," she says.

He stares at her for another minute. There's something unnerving about his gaze, and it's not just his scar. There's a strong intensity behind his golden eyes that unsettles her. He regards her like he knows something she doesn't. She vaguely wonders if she should know who he is.

"I'm Zuko," he finally says, then looks away again. Katara watches him for a moment.

There's definitely something going on. If not with the situation, then at least him. But she has no choice; he's her only way off the iceberg. He's being generous enough to give her a ride, so she can't really be picky.

If there is something more going on, she's going to find out soon enough anyway.

Besides, in a few days she'll be back with her family, her memory restored, and she can forget about this strange boy and his companions.

Sokka dreamt he was eating the best whale steak of his life. He had speared the whale himself during the whaling season and hauled it back to shore on the back of his ship. When he'd reached the docks of his village, all the girls had been standing there, waiting. As he'd stepped off the ship, victorious, they'd followed him all the way back home where he'd prepared the meat, cutting it up, and spending hours cooking the meat to perfection.

Normally, of course, cooking is a woman's job. But Sokka had wanted it prepared a specific way, and he didn't trust his sister - who'd never shown much affinity for traditional feminine roles - to do it right.

Besides, knowing the labor that went into making it just right makes it all the more savory.

He brings the forkful of meat up to his nose and takes in the beautiful aroma. "Mmmm," he says, closing his eyes. He's in heaven. He brings the fork back down and opens his mouth. The meat has just touched the tip of his tongue when suddenly the world explodes around him.

He jerks awake, panting. His mouth is dry and tastes gross. "Not fair!" he complains, hitting the ground beneath him. His fist is met with the cold and hard sensation of ice.

"Where am I?" He glances around and his eyes widen. "Oh…"

All around him is the wide, open sea. He's sitting atop a chunk of ice, being carried by the waves.

"This isn't good," he whispers, staring at the endless expanse of waters around him. "This isn't good at all."