The very bottom of the world was a place that defied expectation and explanation. At least that's how it seemed to Prince Zuko, as he exhaled a puff of heated air that quickly dissipated into the whirling snow around him.

He had been traveling for a week, though he was starting to doubt his own ability to tell time. Leaving the Tiger Seal had seemed so easy; no one had tried to stop him, even as he began walking directly due south. In those first moments of marching, his pack strapped to his back, Zuko thought that maybe this wouldn't be too difficult after all; now, as the snow hit his exposed skin like tiny pinpricks, he found himself reconsidering just how dangerous the weather was, and contemplating with dread how much worse it might become. He was no fool; he knew the South Pole would be cold. He had traveled all over the world, in the first years of his banishment, and had experienced the biting pain of a blizzard before. But he didn't ever imagine it would be like this.

Perhaps the staff of the Tiger Seal had become used to the determination of such travelers, whose ambitions outstripped their sense of self-preservation; if they'd made it all the way to the inn, then they weren't going to turn back because of a few severe weather warnings from the locals. Perhaps they did warn most people—people who could smile, whose faces weren't difficult to look at, whose failure didn't cling to them like a stench that could never be washed off. Perhaps they knew exactly who Zuko was, and thought it was better that he die down here, alone in the snow—one less Fire Nation monster to hunt them and theirs. Zuko wouldn't be surprised.

The snow around him was blinding, the horizon line all but obliterated. Nothing but blank whiteness for as far as the eye could see, and nothing to keep Zuko distracted and prevent his mind from wandering. The cold had numbed his body, dulling the pain in his shins that came from traipsing through the snow banks, but the agony of the mind remained sharp and cruel, no matter where he was.

Bring me the heart of the last waterbender. His father's order echoed in his head, whispering over the howl of the wind. At the time, those eight words had seemed like a benediction, a peace offering, a final trail on the map that could guide Zuko back home. He had wandered the earth for six years after his banishment; he was the Exiled Prince, unwelcome wherever he went. He had held out as long as he could, determined to keep his head high and his pride intact—what was left of it, anyway—before he had come crawling back to Caldera, head bowed low, begging for some way he could be redeemed.

It wasn't the jeers of the peasants that did him in, in the end. It wasn't the news that his uncle Iroh, perhaps the last man who had shown Zuko kindness, had taken ill. It wasn't even the rumours that his sister Azula was being groomed for succession. Zuko had just become too homesick to be afraid anymore.

It was humiliating. Every moment of his return had been torture; sneaking through the city like a common thief, the silence in the palace hallways, his sister's high-pitched giggle heard behind a door as he passed. Zuko had half-expected his father to just kill him on sight; that was the standard punishment for those who broke their exile and returned to the Fire Nation. But Ozai had spared his son the flames this time; as Zuko prostrated himself, his forehead hovering less than an inch from the smooth marble floor of the throne room, the Fire Lord had instead simply waited. Seconds had crawled by in agonizing slow motion, and Zuko never moved a muscle, even as he braced himself to hear the whoosh of fire and feel the heat bearing down on him, searing his flesh, making countless nightmares a reality.

Ozai had made him wait for over fifteen minutes before he finally said those eight words: bring me the heart of the last waterbender.

By the time Zuko raised his eyes to the throne, his father was already gone. He had slipped away from the palace just as quietly as he'd entered, his hooded robes pulled up over his face, had told no one of his new quest. He had boarded a ship bound for the southern tip of the Earth Kingdom, and from there had hopped from vessel to vessel until he'd made his way to the pole, utterly alone. Being exiled was bad enough; to have come back, begging for mercy? That was a whole new level of dishonour, a whole new dark void of self-loathing that could rot and fester in his mind with each passing day.

He stopped his trek for a moment, his upper lip curling reflexively as a wave of shame washed over him. The waterbender will see right through you, the old woman had said. There would be more than plenty for her to see in Zuko; it wasn't a question of whether or not she would find him unworthy, but rather just how many of his transgressions she would drag up as proof before—

He closed his eyes. I won't let her get that close.

There were no other options. There would be no substitute. He would accept nothing less. Crown Prince Zuko of the Fire Nation would return triumphant and take his rightful place by his father's side, and this whole horrible ordeal could just be forgotten.

But Agni, it was cold. Zuko clenched his jaw, trying to keep his teeth from chattering.

The snow came up to his mid-thigh by now, turning each step into an ordeal of quick capture and agonizingly slow release, over and over again. He had packed light, but not light enough; he'd already discarded several less-than-crucial items and was starting to wonder which of the crucial ones he could do without. He had placed them down on the trail, in a vain attempt to mark himself a path home, but when Zuko looked back, all he could see was a blanket of pure white snow, his footsteps disappearing before his very eyes.

He'd stopped to make camp only three times, when the exhaustion had become profound enough that he couldn't drag himself even one step further. Zuko wasn't entirely naive; he had consulted experts, learned how to survive in the winter like this. How to dig himself a burrow in the snow, how to insulate himself as much as possible, how to keep his compass in hand at all times lest he lose his way and go in endless circles.

In theory, that was all well and good. In practice, Zuko had to admit that things were not going quite as smoothly as planned. As he got further to the bottom of the world, the compass seemed to go haywire more and more. He knew that the sun in the South Pole was going to be weaker than he was used to, but as Zuko trekked south, the light dimmed, until one day it disappeared completely. It hadn't risen in days, or at least that's what it felt like. The winds got worse with every passing hour, faster and colder than he thought imaginable. Zuko, who had trouble seeing out of his left eye at the best of times, had completely surrendered all hope of actually being able to watch where he was going, and he grumbled muttered curses into the scarf that covered his mouth and nose from the cold.

"Cold" was an understatement. Cold was a four-letter word. Cold was meaningless, undefined, beyond and without limits. Zuko was the Crown Prince of the Fire Nation, born in the capital city of Caldera, damn it; he had been raised in the sun, as was his birthright. He was a firebender; he drew power and energy from the sun, and the South Pole was one of the darkest places Zuko had ever seen. His Phoenix tail did nothing to shield the wind from his ears, and tiny pinpricks of snow seemed to hit his bare scalp no matter how tightly he retreated into the hood of his coat.

A lesser man might stop, make camp again, try to wait out the storm and resume his journey once visibility was better. But Zuko was better than that; he had to be better than that. He knew that it was no accident that the last stretch of his journey was taking place in such a world of darkness; that was how destiny worked. This was his final test, his chance to prove once and for all that he deserved his title, his family, his place in the sun.

All Zuko had to do was kill an innocent old woman and cut out her heart.

The winds suddenly whipped up around him, almost pulling his coat clean off his body. Zuko gasped as a chill shot straight through him, reverberating in his chest and making his arms tremble so badly that he lost his grip on the compass, which dropped silently into the snow and promptly disappeared.

"No!" Zuko yelled, falling to his knees, digging through the snow to no avail. Visibility had dropped even further; he couldn't see much farther than his own hand directly in front of his face. The cold seemed to be seeping through his thick coat, crawling up and into his skin, settling into his core. He sat back on his knees and closed his eyes, trying to find his root, his uncle's voice rising to the forefront of his mind: fire comes from the breath.

Inhale. Exhale. Zuko could feel his inner fire, burning brightly even as the storm tossed him around. He drew from it and exhaled a long breath of hot steam, hoping to warm the scarf on his face, but the air seemed to go right through the fabric and out into the night.

Fuck. He pulled off one glove and snapped his fingers, pulling a flame out of thin air to sit in his palm, but as Zuko brought his hand near to his face, the fire whipped and flickered and suddenly went out. His second attempt gave the same result, as did his third, before Zuko felt his fingertips go numb and hastily pulled his glove back on to avoid frostbite.

The blizzard wasn't stopping; in fact, it seemed to get faster, the wind coming closer and closer as it circled around him. Zuko staggered back to his feet, only for a huge gust to come up behind him, catching the wide span of his pack and knocking him head over heels, tumbling through the snow. As Zuko rolled, he struggled to disentangle himself before the straps pulled both his arms off; when he was finally able to sit up again, the pack was nowhere to be seen, just another snow-covered lump in a world of nothing but snow-covered lumps.

A surge of rage and frustration blazed through him and he pulled his hands into tight fists, fireballs erupting from each one, burning his gloves away. "You think that will stop me?" Zuko yelled to the sky, his voice disappearing into the howl of the wind, but the fireballs barely lasted three breaths before they were snuffed out.

This had never happened before. Zuko was no prodigy, not like his sister (he knew that all too well), but he had spent his time in exile training harder than he had ever trained before, and his firebending was incredibly powerful by this point. Despite what everyone said in jeering whispers, he was still Ozai's son; there was a flame that ran through his family, and he had it, even if he had struggled to find it initially. That fire didn't just...flicker out with a strong gust of wind; even the most powerful blast from an airbending master wasn't enough to extinguish his power. And yet the blizzard took Zuko's fire easily, snuffing it away as if it had never been. He tried again and again, and each time his flames seemed weaker and weaker. But he had to keep going; his hands would freeze if he didn't.

Something brushed against Zuko's right hip: a tube in his belt with a message scroll, enchanted by the fire sages so that all he had to do was burn his message into the parchment and let the ashes go with the wind. They would travel to their destination and reassemble themselves when they arrived; no hawks required. Zuko could feel the flame of his inner fire blowing and flickering, as if the wind was inside him somehow.

You won't find her; you'll die in the snow first, and no one will know to mourn you. Zuko had felt the woman's gaze on him, back at the Tiger Seal, and he'd looked away like a coward. Now her warnings were coming back to bite him.

With his hands shaking, he pulled the scroll out and managed to conjure up a weak flame. He inscribed his message—I am Prince Zuko. I'm trapped in a storm, a week's walk south from the Tiger Seal inn. Send all available ships—and let the flame catch the paper, huddling over it so it wouldn't die out. The ashes rose into the air, the flecks of grey swirling around him like a tornado, caught by the winds and unable to break free. Please, he begged silently. Please find someone. Anyone. I can't stop here, not when I'm so close.

Nothing changed; the blizzard continued its relentless onslaught, creeping ever closer, trapping him in. I have to get to shelter, Zuko realized. I have to wait out this storm.

There was part of him, the cowardly and soft part of him, which knew that the storm could probably outlast him, instead of the other way around. Nonetheless, Zuko fell back to his knees and began trying to dig a cave in the snowbank, hissing in pain as his fire failed to protect his hands and his fingers began to freeze. The wind surged up again, blowing his hood off and wrapping his hair around his throat. He gasped, clawing at his neck, but he was trapped and blind and definitely not starting to panic—

He couldn't breathe. It was impossible to be calm if you couldn't breathe. Zuko pulled his knife from his belt, but his hands were trembling too much to risk bringing the blade anywhere near his throat, so he reluctantly reached up and began to slice off his Phoenix tail at the root, wincing as the knife jittered against his bare scalp. After a few tense moments of cutting, his hair fell away and Zuko gulped at the icy air, shivering as it entered his lungs.

Agni, I swear I'll never fight with Azula again if you let me live through this, he thought despite himself. I'll light an offering at Grandfather's tomb every day for the rest of my life. I'll obey Father's every command. I'll stop searching for Mother. I'll—

Zuko's eyes widened as the uniform white of the snow was broken by a dark silhouette that seemed to glow light blue around the edges. He opened his mouth to yell for help, but he couldn't make a sound; the cold seemed to be inside him now, crawling and spreading, freezing him from the inside out. The shape came closer, resolving into the unmistakable outline of a human being.

It's her, Zuko realized. It has to be her. She's right there; she's come to me. I could end this right now. If I can just—

A final wave of cold air slammed into him, and Zuko only had the briefest vision of a flame snuffing out before his head hit something hard and the darkness swallowed him.

.

In his nightmares, Zuko saw an outline of a woman in the snow, and he reached for her with a weak and trembling hand. She knelt down, murmuring something he couldn't quite make out, but her presence was soothing and kind and achingly familiar—Mother.

"There you are," she said, in a voice not quite her own. "I was worried about you."

Where are you? he tried to ask. Where did you go? Why did you leave?

His mother shook her head, as if she didn't even hear him, and reached out to the place just under Zuko's left eye—

No, he pleaded, reaching out and catching her wrist before she could touch the scar. Not like this. The only good thing that came from you leaving is that you never saw me like this.

His mother smiled sadly and began to fade from view. Normally when he had this dream, Zuko would chase and chase without ever catching up to her; this time, he realized, he couldn't move his legs at all.

Please, he thought, his voice cracking with tears even inside his head. Please don't let me—

.

—he bolted upright, gasping for breath, crashing back into the waking world just as suddenly as he'd left it. His heart raced as his eyes slowly refocused and the blurry shapes all around him began to sharpen and resolve. Zuko was no longer stranded in the storm; he was in a room with clean white walls that seemed to smoke very gently, giving off odorless vapour that coated the floor like a thin mist. Instead of the snowbank, he was lying in a bed, covered in furs and blankets, his chest bare.

What the—

"There you are," someone said—the same voice from his dream. Zuko blinked as the door in front of him opened and a young woman slipped inside. She couldn't be much older than he was, probably only nineteen or so; her skin was smooth and brown, eyes clear blue like gems, and she wore the unmistakable blue robes of a member of the Water Tribe.

"Where am I?" Zuko asked, wincing his demand coming out as an embarrassing croak. "Who are you?"

"Relax," the woman said, her voice soft and unhurried as she approached the bed. "You're safe. My name is Katara. I found you lost in the storm; you stumbled into quite the blizzard out there."

"You're telling me," he scowled. "How long have I been here?"

Katara shrugged. "Two weeks, give or take."

Zuko cradled his aching head in one hand, barely suppressing a groan. He'd been waylaid by half a month because of that Agni-cursed storm; he had no idea where he was, never mind any of his gear, so that was all going to be a pain to sort out before he could get back on track. With a huffed sigh, he threw the blankets off and swung his legs over the side of the bed.

"Oh, no, I wouldn't—" Katara began, but she was cut off as Zuko tried to stand and promptly collapsed into a heap on the floor. He groaned as she knelt beside him and helped him back up.

"Yeah, that's not going to happen for a little while, I'm afraid," she said once they settled back onto the bed. Zuko let out a shaky breath, watching his legs tremble from the exertion.

"What—"

"—You were out in the storm for...well, I don't know exactly how long, but you were dying. I brought you back here, and I've been healing you ever since, but it's going to take some time."

Zuko exhaled tensely, through pursed lips. "Great," he sighed.

"Can you tell me your name?"

Remarkable. It had been so long since no one had recognized him, and it made Zuko feel strangely calm. He exhaled again, smoother this time. "Zuko. My name is Zuko."

Katara held out a hand, which he shook reluctantly. "It's nice to meet you, Zuko," she said. "Would you like something to eat?"

At the mention of food, Zuko's stomach growled loudly, and she smirked.

"I'll take that as a yes, then."

As Katara rose to leave, Zuko finally looked down at his chest, where an ugly red scab now sat directly over his heart. He winced, shivering as he recalled how the cold had seemed to crawl into his body and consume him from the inside out. Hypothermia is a hell of a thing, he mused to himself. I can't believe I thought that my firebending was—

He stopped.

The room was warm, but Zuko still felt cold, and something was off; something was wrong in his chest. He reached for his inner fire and came up with nothing. It had never been this weak before. It had never been this quiet, this tiny, this dim.

Zuko looked up, eyes wide, and saw Katara standing at the door again, now holding a tray of food. He looked back down at his hands and snapped his fingers, but nothing happened. He reached again for his inner fire, more desperately this time, but all he felt was a bitter spike of cold.

Where is it? What's wrong with me?! Zuko felt panic start to consume him as he desperately searched inside his mind, trying and failing to grasp any semblance of the heat he'd felt his whole life, and flinched away violently as Katara set the tray down on the mattress beside him.

"Zuko, listen—"

"What have you done to me?" he gasped, too shocked to try and cover the fear in his voice. "Why can't I bend?"

Katara raised both hands. "Please try to be calm," she said, which only made the creeping panic worse.

It was all wrong, profoundly wrong, badly wrong. He felt empty, hollow, dark. Zuko swallowed around a huge lump in his throat, his heart pounding as he grasped the truth:

His inner fire wasn't just weak; it was dead.

Katara's features began to swim as tears filled his eyes. She went to place her hand on top of his, but he yanked it away, and she sighed.

"The storms up here are full of magic," she murmured. "From the moon, and from the South Pole itself. The wind and the cold caused damage to your heart, and—and your chi is blocked."

He sat back, hitting the headboard with a thud, shaking his head in tiny motions back and forth, dreading the words he knew he was about to hear:

"I'm so sorry, Zuko. Your bending is gone."