A/N: So, I haven't tried writing this fandom before, but I adore Zutara, so here goes. I hope you like it. Much love! xx-Kitten.

Brightest Nights or Darkest Days

By Kittenshift17

CHAPTER ONE

She'd happened upon him by chance. A pure coincidence that had proved entirely too beneficial. Three weeks past, Katara of the Southern Water Tribe had been separated from her brother Sokka, her best friend Avatar Aang, as well as Appa and Momo during the terrible blizzard that had ripped across the four nations with all the wrath of avenging spirits brought to life and seeking vengeance.

Katara had been thoroughly lost in the wind and snow. Unfamiliar with the territory she roamed on foot, confusing landmarks she remembered from the South Pole with those of her current surroundings. She'd been forced to steal clothing and supplies along the way – having lost all but the clothes on her back when she'd been torn from Appa's back amid the blizzard and hurled away in the wild winds and teeming snow that had ravaged the land.

She knew there had been something otherworldly about the blizzard that had descended upon the land. The Earth Kingdom was not a place where such heavy snows and wild storms blew. She'd had to make do with what little she had – and she didn't have much of anything at all. She'd stolen a small rucksack from the first house she'd found, stealing clothing, food and supplies from there while the family slept.

She hadn't taken enough to leave them short, but she'd taken what she needed. Despite being lost and alone with no real means to contact Aang or Sokka, and no clue where to begin looking for them, Katara had resorted to disguising herself. And she still felt surprisingly upbeat. She was at home amid the snow and the ice – even if she did get a little turned around a few times. A water bender's favourite place to be was surrounded by water – no matter the form it took.

And having grown up in the South Pole, the driving cold and fluffy flurries of snow felt like a little slice of home. She'd taken to wandering the towns near where she had landed, searching for some sign or whisper about the Avatar being in the area. And it was through this practice that Katara had begun to learn many valuable things. The first and foremost being that in addition to Aang being wanted by the fire nation, she and Sokka were also listed as wanted fugitives. When she'd first spotted the poster she had been quick to change her clothes from the tell-tale Water-Tribe blue to a dull and boring brown set she'd pinched from an abandoned home.

She had also learned that the blizzard was unnerving everyone – yet some rejoiced for it had temporarily stilled the wheels of war. Katara knew this because last week she'd been involved in an uprising in a town many miles back where the local benders had risen up and overthrown the suddenly cold-weakened Fire Nation soldiers. It seemed that while the benders burned hot enough to tolerate the chill, prolonged exposure to the driving cold and inability to access the heat of the sun was weakening even them.

Katara believed it to be Karmic justice. The very world fighting back against the Fire Nation that had so ravaged and pillaged the land and its people.

She had come upon the least likely of people whilst searching for her friends. In addition to learning that she and Sokka were Fire Nation fugitives, she had learned that Prince Zuko and his Uncle Iroh, were also wanted renegades. She had spent many long minutes studying the other wanted posters when she'd discovered them, reading the crimes of all. She knew there was someone masquerading as the Blue Spirit who was wanted for a long list of crimes, including freeing and kidnapping the Avatar. Katara remembered that Aang had mentioned being saved by a silent man in a blue spirit mask.

She had stumbled upon him by accident three days ago as she'd been stealing food, fishing for information on her friends and removing every Fire Nation wanted poster featuring her and Sokka that she could find. There was little point removing those of Aang. They'd been up too long and everyone knew the Fire Nation wanted the Avatar.

She'd taken to following him.

Zuko.

Her first thought when she'd spotted him had been anger, followed quickly by confusion. Like her, he was masquerading as someone else. He'd stolen Earth Kingdom clothing, as she had, and had even adopted a new name. He was calling himself Lee. And he was travelling alone. Katara suspected that much like her, he had been separated from his Uncle in the blizzard. She knew they'd been on Aang's trail again. She also knew that if there was ever anyone who had the ability to track down Aang, it was Zuko. He'd chased them clear across the world and back again.

She didn't know how he did it, but somehow he always found them. And she was relying on that ability and his willingness to do it again as she tailed him. At first, it had been curiosity and concern, fear of what havoc he might be wreaking. Then it had been her plan to use him to lead her to Aang. However, as she'd followed him, she'd learned some things about Prince Zuko that she'd never thought she might discover.

The first and most important thing being that he was the Blue Spirit. She knew because she'd watched him don the disguise before liberating several Earth Benders from a detention camp across the city. He'd been utterly ruthless against his own nation's guards, slicing and hacking at them with deadly precision, ending lives wherever he went. He never used his bending – clearly not wanting to give himself away – but she'd learned that in addition to being a determined, dedicated and powerful bender, he was also a weapons master. He wielded blades with as much precision as he wielded fire.

She was following him now, having entered the same tea shop he'd gone to and ordered herself a cup of jasmine tea with some coins she'd stolen from Fire Nation soldiers. It seemed he either really liked tea shops - though he always made a face whenever he ordered a pot of tea for himself - or he was searching for his uncle in the tea shops. Katara supposed that made sense. Tea shops were places where gossip was bandied about rather freely, and what she recalled learning about Iroh was that he was very fond of tea.

She knew he'd noticed her a time or two in the days she'd been following him. She'd played it off as them simply being two travellers searching for lost friends who happened to be travelling the same direction. He'd been suspicious enough the previous day that he'd made to confront her and Katara had been forced to slip inside a tavern and play at being interested in a man she met there to avoid him.

Currently Zuko was sipping tea and glaring around the tea shop with distaste. It wasn't a particularly pleasant shop and when she tasted her own tea she made a face over the disappointing flavour. The leaves were clearly old and stale – and the water to brew them only just tepid. She'd been watching Zuko closely enough that she'd seen him react to the tea the same way she had, before he'd very subtly breathed heat into the cup until it had begun to steam pleasantly.

She eyed him carefully from the confines of the thick hood she wore to disguise the tribal colouring of her skin and to protect herself from being spotted and recognised. A thick scarf wrapped around her throat, concealing the water-tribe necklace she wore and her hood concealed her long dark hair. As she watched, the sound of raucous laughter drew her attention and Katara looked in the direction of the entrance to see some fire nation soldiers entering the tea shop. They were all fire bending openly to combat the cold of the snow outside.

When they began moving around the shop with a wanted poster, asking people if they'd seen the Blue Spirit, Katara saw the way Zuko shook his head, his identity also concealed by a thick hood that guarded against anyone spotting and recognising the scar across the left side of his face. The guards moved on from him quickly and Katara disagreed to having seen the Blue Spirit before abandoning her tea and leaving the shop – as Zuko had just done.

She followed him leisurely, wandering the market place. She'd learned the hard way that it was easier to tail someone by blending in and seeming like you were meant to be somewhere, rather than skulking about and acting suspicious. More than once in the last few days Zuko had looked right at her, a frown of confusion wrinkling his brow but Katara had been doing a good job of making it look like she was meant to be wherever she was. She roamed the market place, watching him subtly ask people if they'd seen or heard of anyone else lost in the blizzard who might be looking for someone named Lee.

She'd learned his uncle was going by Mushi instead of Iroh, but everywhere he asked, no one had heard of anyone matching Iroh's description. Katara looked up as a rare ray of sunshine beamed through the clouds overhead as she tailed Zuko toward the edge of town. It was getting late in the afternoon and the sunshine was the first she'd seen in three weeks.

She wasn't the only one effected by its warmth. Katara bit her lip when she noticed the way, up ahead, Zuko tipped his head back, his eyes closing and his hood falling back as he practically absorbed the sunshine. Literally. She could almost see him soaking it in like a dawn-blooming flower opening under its tender rays. She knew the feeling. The moon had a similar effect on her when it was full, making her feel alive and vibrant. When it rained she also enjoyed the feeling of soaking up her element.

What Zuko didn't see, however, was the group of Fire Nation soldiers at the other end of the street. They'd stopped to bask in the late afternoon sunshine and were looking around suspiciously, clearly thinking that if the sun had that effect on them, it would also have that effect on any other fire benders in hiding. Which was surprisingly smart for soldiers, given that it was working on Zuko.

They started towards him slyly, shoving each other a little and Katara panicked. He couldn't be captured. She didn't at all like or trust Zuko, but she didn't want to see him captured and hauled off to the Fire Nation. Not when his own father – the Fire Lord – had issued a decree that he was wanted, dead or alive. They would kill him for sure, or he would be forced to massacre them in the street – which she suspected would be the more likely of the two. And that would make it much harder for her to trail him when he finally began looking for Aang rather than his uncle again.

Breaking into a jog, Katara hurried towards him.

"Lee!" she called, affecting an excited tone of voice as though she had just spotted him and was thrilled to see him.

His eyes jumped to her as she came closer and she saw him tense, frowning in surprise. Katara ran a little faster, being sure to keep her hood up to hide her own identity before those soldiers could get two for the price of one. When she reached him, Katara threw herself at Zuko, latching her arms up over his shoulders and letting her momentum propel her forwards, wrapping her legs around his lean hips.

"Don't do anything stupid or you'll get us both killed, Zuko! There are soldiers coming right at you!" she growled in his ear immediately, pressing the side of her face to the scarred side of his, her lips at his ear.

For his part, Zuko handled the situation well. She'd been half expecting he would fire bend at her or at the very least that he would pull a knife on her. Instead she felt him tense against her, his strong, lean form bracing to catch her and hold her up. His arms came up around her, clutching her to him painfully tight and Katara winced at the embrace as she felt him spin her a little, carrying her easily and pressing her into a nearby wall.

Peeking over his shoulder she could see the soldiers still eyeing him suspiciously and Katara resorted to desperate measures, pulling back from him a little, Katara brought her hand up to cover his scar, dragging at his hair to better hide the tell-tale red blemish. Without pausing to think about what she was doing beyond acting to survive and to throw suspicion off the two of them long enough that the soldiers would get bored and forget that Zuko might be a fire bender, Katara ducked her head and pressed her lips firmly to his.

Zuko tensed, his mouth hard and unresponsive against hers until she pulled a little more viciously on his hair and nipped at his bottom lip punishingly. Her eyes rolled behind closed lids when he suddenly leaned into her, kissing her back fiercely and pressing her into the wall harder. She'd positioned herself rather unfortunately so that his hard, lean body was pressed against the most intimate part of her, her legs tight around his waist, her ankles locked against his back.

When he nipped her lips in return, Katara gasped at the sensation and she realised what a mistake she'd made when his tongue darted into her mouth, tangling with hers in a way that ought to be illegal. Her heart was racing in her chest for fear of being discovered by the soldiers, fear of being attacked by Zuko, and horror with herself when she felt delicious heat pouring through her body, emanating from him like she'd stepped into a steam-room. His lips and tongue were hot against hers, warming her chilled face and making her ache just a bit with the sudden and startling difference in temperature.

Her pulse stuttered in her veins as she felt the strangest brush of something against her. Not against her skin. More like there was something brushing against her chi – her very essence. Something hot and unforgiving as it surged against her and completely enveloped her chi, wrapping as tightly around her as Zuko's arms were around her waist. She felt a quivering sense of utter terror and just the hinted tingle of wonder when she realised it was his essence. His chi enveloped her own essence, threatening to overwhelm it.

She didn't know which one of them it was that emitted the groan at the entirely intimate and slightly uncomfortable yet totally thrilling feel of their chi so entwined. All she knew was that it made her brain go fuzzy and she found herself kissing him not only to hide his identity and her own until the soldiers got bored, but also because it felt completely intoxicating.

Katara kept one hand tangled in his hair, securely concealing his scar until such time that the soldiers left and he could pull his hood back up. The skin of his scar was silky beneath her fingers and Katara felt him tense as she brushed her thumb over it, intrigued. He broke away from her lips with a sharp gasp and Katara hissed in a breath between her teeth when he nuzzled his warm face into her neck, exposing the flesh there before pressing little wet kisses to the skin.

"Are they gone?" she heard him ask and a chill slithered down her spine - despite his overwhelming heat - at the sound of his voice, tight and controlled and utterly devoid of any emotion but anger. She loathed that voice. Peeking through slitted eyelids, she nearly closed them again in horror when she saw that the wretched soldiers had stopped advancing and lost interest in questioning Zuko. They were focusing on something else.

"They're watching," she breathed. She was trying not to pant as a result of the way he nipped and kissed her throat like a hungry beast. She marvelled at his ability to make it appear and even feel like he was into it, whilst she could still feel how tense and tight his body was between her legs – coiled like a viper and ready to strike at any moment.

She felt her cheeks beginning to turn pink as a gust of heat caressed her skin when Zuko sighed out an annoyed breath. He nipped her throat hard enough to leave a mark. Almost as though to punish her for the ludicrous position he'd found himself in. As though she hadn't thrown herself at him to protect his identity and save his life. The soldiers were leering in their direction, nudging each other like stupid children and clearly finding amusement and twisted pleasure in the show she and Zuko were putting on. Katara felt like she was being ripped apart and put back together in the wrong ways, horrified with herself that she'd just kissed and was still snuggling the enemy but hating herself all the more for the fact that her body and her essence were reacting to his touch and his attentions favourably.

What was wrong with her? Had she lost her mind?

"Three feet to the left is an alley," she whispered, scanning their surroundings carefully through her eyelashes. She hardly dared open her eyes wide enough to see without being spotted for an imposter by the soldiers.

"You want me to take you in an alley?" Zuko sneered against her neck, pressing into her harder, one hand clenching in the fabric of her clothes. Katara's cheeks burned crimson at his wording and his smug, patronising, wickedly amused tone.

"I want to get out of their sight so I can run for it," she corrected him. She nuzzled her own face into his cheek under the pretence of returning his affections before she nipped his jaw harshly, causing him to twitch and buck against her slightly.

Unhooking her ankles from around him quickly, Katara lowered her legs back to the ground, standing on her tip toes a bit under the pretence of kissing him again. He'd begun to chuckle cruelly until she pressed her lips to his severely, pouring her disgust with herself and her annoyance with him – not to mention her hatred of him – into the second kiss. As she did so - her mind threatening to go blank and not care about anything but those licks of heat that seemed to emanate from him – Katara tangled her free hand into the front of his clothing and half dragged him around the corner and into the alley.

She heard a catcall from the street, the soldiers laughing and jeering now, sounding like they might follow to see more of the show. As soon as they rounded the corner and were out of sight, Katara jerked back from his lips, hissing at the unpleasant feeling of ripping her essence free of his own suffocating one.

"Run!" she commanded. She tugged sharply on the front of the travelling robes he wore before she made a break for it down the alley to the opening she could see at the far end through a little sliver of space.

It was too narrow for them both to fit through and the rest was a five foot wooden fence. She could hear Zuko pounding along the alley a step behind her and she realised she was going to have to water bend or jump the fence. And with the soldiers now shouting from the mouth of the alley and suspecting foul play, bending didn't seem wise. Her eyes zeroed in on a stack of wooden crates and she used them as her springboard, leaping onto them and using their added height to propel her over the fence.

Zuko followed right behind her and Katara had to crouch into a squat on the landing to keep from being hit by him as he sailed over her to land a few feet beyond her. Springing right back up, she glanced around quickly.

"This way," he growled. His voice sent another chill down her spine as he snagged her elbow before tearing off down the darkened street. He seemed to know where he was going and their running had drawn the attention of more soldiers, so Katara chose to simply follow him as he led a merry dance through the streets, stumping the soldiers and outwitting them.

As she leapt over another fence behind him, she was about to keep running but he spun as he landed and caught her before she could hit the ground. Katara cried out in surprise as he spun with her momentum before hauling her right through a small wooden door just next to the fence. He kicked it closed and used his fire bending to melt the metal lock shut before turning on her and slamming her into the wall in the dark and abandoned room.

"Who are you?" he snarled into her face. He curled his hand around her throat, pinning her by it.

In the other, he held a fireball threateningly, as though he would throw it at her if she didn't answer. She didn't at all doubt he would. He was a ruthless killer with little conscience. Despite the way her mind demanded she claw at the hand cutting off her air supply, Katara reached for her hood, meaning to lower it.

"You again!" he suddenly said before she could reveal her identity. "You've been following me. Who are you and how do you know who I am?"

Katara rolled her eyes at the cold fury in his voice before she lowered her hood away from her head, revealing her face and hair to his narrowed gold gaze. She stared back at him defiantly as he glared at her for a minute in complete silence, his features devoid of any expression but anger. She thought for a moment that he must not recognise her.

Until he suddenly took a big step back, freeing her throat to wipe the back of his hand against his mouth.

"You?" he cursed. "You kissed me! What is wrong with you, Katara?"

He looked revolted, wiping his hand against his mouth again before spitting on the floor.

"Gee Katara, thanks for saving my life even though I've been nothing but a selfish bastard who stalked you across the world and nearly killed you and your friends in many unsuccessful attempts to capture the Avatar," she bit out sarcastically, glaring at him. "Yeah, no problem, Zuko."

He narrowed his eyes on her at the mention of his name and no doubt at her rudeness.

"Assaulting me does not count as saving my life, water bender!" he snapped. "What the hell are you doing here? Why were you following me?"

"Who said I was following you?" Katara countered. She stepped away from the wall where he'd pinned her and stalked off through the building he'd dragged her into. It was an abandoned house. Most of the furnishings and things had been looted, leaving it bare and devoid of much at all. Narrowing her eyes and wondering why he'd brought her there, Katara stomped through the place.

She smirked when she climbed some stairs – with Zuko, still snarling, on her heels – and found a small palette where he must've set up camp for the night. She'd yet to do so, having been following him most of the day. He'd escaped her for a little while when she slipped off to the bathroom, and this was clearly where he'd gone. She could tell they were his things because she'd been watching him long enough to recognise them.

"You have been following me," he accused. "You're not exactly subtle. Where are your little friends? Where's the Avatar? And since when is it you stalking me and not the other way around?"

Katara smirked at him for his wording, watching him flick a ball of fire towards a small lamp by his things to light the room without needing to hold the fire himself. It was sealed closed against the cold wind outside – though she could hear it whistling through the small cracks in the window frames. He'd chosen what seemed to be an abandoned study, rather than one of the bedrooms, and it had no windows. She frowned at the idea. Windows would make for an easier escape, but then again, the building was abandoned and he was a strong fighter. Maybe if he was ambushed he meant to fight his way out – avoiding detection by hiding somewhere that no one would see the light of his fire.

"If I lack subtlety so much, you'd have known it was me and you'd know why I've been following you," she informed him. She moved over near the lamp he'd lit before sitting down on the ground and taking out her rucksack – which she'd taken to wearing against her skin under her clothes for better warmth.

She caught the way Zuko's eyes widened momentarily as she lifted her many layers of clothes to get at the meagre bag of supplies. He narrowed them on her again at her evasiveness.

"Answer me," he commanded.

"I'm doing the same thing you're doing," Katara shrugged. "Trying to find my travelling companions after being separated from them in that blizzard a few weeks ago. We were on Appa when it struck and I was blown free of his saddle."

Zuko curled his lip.

"Then why are you following me?" he asked. "Shouldn't you be trying to find them?"

"I am trying to find them," she replied. "And so are you. And since you managed to track us while we rode a flying bison all the way across the world and back again, I knew that if anyone could find Aang, it would be you. I intended to merely follow you in your search for them and your uncle until they were found."

"Then do tell what you were doing ambushing me and kissing me," he demanded. He looked like he didn't know if he should be flattered by her belief in his ability to find Aang or disgusted with her for changing her plans and kissing him instead.

"The sun came out and you were like a Morning Glory, soaking up its rays in plain sight. Your hood fell back and those stupid soldiers saw." Katara shrugged. "And you're no use to me dead or imprisoned…. It's not like I know much about tracking the Avatar. Usually I'm one of the ones being tracked. I just reacted."

"By kissing me?" he asked,

"Oh for crying out loud, would you stop saying it?!" Katara lost her temper with him. "I didn't think about what I would do after calling out to you and I knew if I didn't do something, you'd throw me off you and demand to know who I was, drawing the attention of those idiots all the more. A random case of mistaken identity and subsequent fight is more noticeable and memorable than two teenagers kissing in an alley."

He narrowed his eyes on her but didn't say anything else and Katara turned her attention to digging into her rucksack for something to eat. She had a bag of dried fruits and nuts and she hadn't eaten in hours. She was also shivering. Her body seemed to be going into a mild state of shock after being pressed against - practically enveloped by - someone so warm and it had thrown her body temperature out of whack.

Zuko watched her a minute longer as she began to eat her food before he started muttering under his breath too low for her to hear. He threw himself down on the palette he'd set up earlier and began rummaging in his pockets for some of the food she'd seen him buying. A strip of jerky was all he pulled out and Katara watched him as he began to chew on one end of it.

The silence between them was strained and awkward as they ate. Katara found herself huddling closer to the lamp he'd lit, trying to absorb some of its warmth. She nearly leapt out of her skin when Zuko nudged her with his foot.

"Hey!" she hissed. She looked up, worried he was being mean. The angry words she'd been poised to spit died on her tongue when he handed her a strip of jerky. "Oh… um… thanks, I guess."

She offered him the bag of fruit and nuts she was eating from in return, figuring he must only be offering her some of his food if he wanted some of hers in return. He eyed the bag for a minute before cupping one hand, waiting for her to pour some of the snacks into it. He nodded when he wanted her to stop pouring, but still didn't speak again.

"I take it this means you've changed your plans about continuing to stalk me?" he said finally, after what felt like hours. The tension was thick in the air. Katara knew it stemmed from the awkwardness of the searing kisses they'd shared in the alley and the burning hatred between them from their past.

"Why bother pretending that I'm not following you now that you know I am?" she shrugged. "I haven't changed my mind about you being able to lead me to Aang – just about whether or not I'll have to interact with you while you do it."

He glared at her.

"What makes you think I'm just going to lead you to the Avatar? Or that I'll let you tag along with me?" he demanded. Katara watched as he dug into his bag and withdrew a battered looking teapot and two cups.

He took the lid off the pot and held it out towards her. Katara realised he didn't have any water to put in it and she narrowed her eyes before summoning her bending power to draw some of the heavy snow from outside in through the house to fill the pot.

"What makes you think I won't just follow you and turn up all the time annoying you if you try to stop me?" Katara countered. She handed the teapot back to him when it was filled with water. She was grateful when he took it without a word before withdrawing a small box of tea from his bag and putting some of the leaves in the water. He replaced the lid and held the pot by the handle before using the closed fist of his other hand to fire bend a steady flame to the bottom of the metal until it began to whistle, indicating that it was boiled.

"I can take you in a fight, Water Bender," he reminded her. "And I'm not afraid to hurt you."

"But you won't," she said knowingly. She took the cup he poured for her, curling her hands around it greedily and soaking as much of the heat as she could into her skin.

"Nothing has ever stopped me before," he said as he sipped his own tea. He still looked like he didn't like it very much. In fact, she got the feeling he only drank it for the warmth it provided and the familiarity of sharing a pot of tea while in company.

"No, but without your uncle around, you're just as on edge and lonely as I am without Sokka and Aang," Katara said quietly. "It makes sense to travel together until we find them."

"And if I find my Uncle first?" he asked.

"Your uncle isn't a ruthless killer with no conscience and he wouldn't hand me over to the Fire Nation. Besides, it's not like you could do hand me over to collect the reward for my capture. And it's not like finding him would change your goal to find Aang."

"You'd stick around?" He snorted. "But I bet that if I found the Avatar first, you'd probably freeze me to the floor and leave me for dead. Sounds like you need me but I don't need you for anything… and in case you've forgotten, my uncle might not be ruthless and without conscience, but I am."

"I'm not scared of you, Zuko." Katara rolled her eyes at him.

She nearly had a heart attack when he suddenly lunged at her, tackling her across the floor.