Zuko sighed as he walked down the palace hallway toward the library. After ten years of being Fire Lord, he didn't expect to be staying up late to research old laws from books hiding deep in the library. And here he was, getting ready to exchange one pile for another. Grumbling, Zuko pushed open the library doors and followed the aisles toward the politics section. Several librarians waved cheerfully at him. Truth be told, Zuko liked working in the library. He'd found a nice little nook by a window, and even if he did lose hours watching the world outside, he never minded. It was a very comforting place.

One thing he didn't expect to hear, though, was humming. Zuko stopped at the end of a row of shelves, and almost instantly he knew who it was. The tune was light and airy. Whimsical, his uncle would call it. With a deep breath, Zuko forced his feet to move, fully intending to walk past Katara, leaving her to complete her task while he finished his. It was late, he had lots of work to do over the next few days, he should really be getting some sleep. Zuko focused very hard on keeping his eyes in front of him as he walked and the humming grew louder. Why was he even acting this way? It wasn't like he hadn't stumbled across her before, exchanging pleasantries or a quick hug in the hallway before going about their business. They'd shared lunch in the gardens too many times to count, spent evenings talking about nothing and watching the turtleducks. Her presence in the palace was just as normal as anyone's. Half the time, when people were looking for Katara, they came to him. They were friends. Good friends. More than friends.

Slowly, Zuko peered around the bookshelves, and there she was, humming as she flipped through a book before shaking her head and putting it back. Zuko swore that he didn't notice a thousand little things about her, like the way that her hair was slightly damp, as if she'd just gotten out of the bath, or the specific way the corner of her mouth tilted upward when she was trying not to smile. He certainly pretended that he didn't notice the way that her robe slipped open as she stood on the tips of her toes to reach a book on a higher shelf, exposing just a hint of skin to him. And he certainly hadn't thought about that skin, because it would be inappropriate to think about the way that skin would feel against his. How soft and how pleasant, and would she smell more like summer rain or the southern sea, because those were two scents he always associated with her. Did she associate any smells with him? Did she think of him whenever she was by a warm fire? She'd once made an offhand comment about him and fire lilies, but he'd been too busy watching the way her mouth formed the words to pay attention. She'd been making him feel like an awkward teenager more and more lately, and he couldn't quite figure out how he felt about that. He was supposed to have grown out of his prolonged awkward teen phase. Uncle had promised him it wouldn't last forever, and yet here he was, a grown man still reduced to stumbling over his words.

Zuko groaned, hitting his head against the bookshelf. He was doing it again, letting his mind get lost in thoughts of her. And then he hit his head once more for good measure, cursing his stupidity, because now she was making a surprised noise and shuffling about, and she probably realized that he'd been standing there watching her like a creep for who knows how long.

"Zuko! Hi!" Katara hastily shoved a book behind her.

He didn't notice the way she took half a step toward him. He didn't notice the way she smiled at him, full and welcoming, didn't notice the way her cheeks colored an enchanting shade of pink. He didn't notice the way that her eyes roamed over him or the way she was taking a series of calming breaths.

"How long have you been here?"

Zuko tried to think of something normal people would say.

"I have books."

That was not a normal response to her question.

"I can see that," she said, with a beautiful laugh.

Zuko took a deep breath and walked into the alcove, setting his books on the table, and hoping like he'd never hoped before that he wasn't blushing. Honestly, he should be able to keep himself together better than this. They'd been best friends for years, had spent countless hours with each other. He'd watched her grow and become an incredible person with so much to offer the world. He'd been there as she matured and became an amazingly beautiful young woman…

"Did you need some help?" he said, stumbling over his words as he gestured toward her books.

"No, no," she said, turning a deeper shade of pink. "I can get it."

"You're not tall enough to reach the shelves."

"I can get a ladder."

"But I'm right here."

"I don't want to trouble you."

Zuko sighed. "I already know you read cheesy romance novels, Katara."

"Don't be silly, I wouldn't read that stuff."

Zuko couldn't help the smug smile as he gestured to the books around them. Four whole cases of exactly the kind of melodramatic, clichéd romance novels that bored, middle aged housewives and his uncle simply adored. Katara crossed her arms and huffed, turning her head slightly away from him. Try as he might, there was no way that he could keep his eyes off the curve of her neck, the way it flowed down to her collarbone, the way he could trace that down a few more inches before her robe hid her from him. And if he wasn't blushing before, he was then, because Katara was watching him from the corner of her eye, and maybe it was just his imagination, but Zuko could have sworn she took a few deep breaths, squeezing her arms tighter around herself and giving him a little glimpse of what was hidden beneath the robe. He licked his lips. She was naked underneath. Spirits help him.

"Maybe I could use your help," she whispered. Breathless.

Katara picked up a book from her pile, handed it to him, then pointed to a place on the shelf. Zuko tried to think of something to say, some topic to keep the conversation going, but his mind was too busy trying to not think of her without the robe, and really, this would all be so much easier if he could just force himself to say something, to just ask her like an adult would do and not wish and hope like he was still an unsure sixteen year old. Since he didn't trust his brain to form a coherent sentence, he just stayed quiet and accepted each book she handed him until the pile was all gone and they were both left standing awkwardly with nothing to do.

"So…" She shrugged.

"I…" He took a step toward her, his heart beating so loudly that he could barely hear himself think. "Katara, I…"

She touched his hand and it was like lightning shot through him, and he threw caution out the window, closing the gap between them, and he didn't think they'd ever been this close before. Zuko ignored every alarm in his head and kissed her. She gasped, but her shock didn't last long. The nervousness bled out of Zuko the moment she firmly gripped his hand, lacing their fingers together, and he cupped her cheek, feeling a great swelling in his heart as she kissed him back. Her lips were incredibly soft, and she stepped closer, grabbing his shirt as she stood on the tips of her toes, pressing her body against his. Things were shifting inside of him and between them, and he moved his hand from her cheek to her neck, and she moaned, and there was no more space between them, but she kept pulling. When she opened her mouth to him, Zuko felt dizzy, letting go of her hand to hold her hip, as if that would keep him from falling, and when she ran her fingers through his hair, he knew that he had to move away from her, that his brain was going to completely shut down if he didn't take a moment to breathe.

When he stepped back, he could feel Katara resisting as if she didn't want to let him go, but she did, and with a few quick steps, Zuko was at the window, throwing it open wide. He took deep breaths hunched over the windowsill, trying to steady himself. His knees were weak. This was like his first kiss all over again only a thousand times more intense. He glanced over his shoulder, and Katara was standing there, her eyes closed and her fingers on her lips. Slowly, she looked at him, beautiful blue eyes almost glistening in the light. Then she smiled the most mischievous smile he'd ever seen her smile, and Zuko knew that, whatever happened next, there would be no going back.

"I wasn't sure," she said quietly.

Zuko turned to face her, sitting down in the window seat. He wanted desperately to say something to her, to explain that he'd wanted to tell her for years, but could never find the right words or the right time. He wanted to tell her how many times he'd thought about her and wondered if he was just making things up, or if she really did invite him into her room or if them going to the play together was really a date.

"I wasn't sure," he parroted back at her, rubbing his face with trembling hands.

"About me?" She came to him, standing between his legs. "Or about you?"

"All of it."

He took a chance and placed his hands on her legs. He pulled her closer, and when she leaned down, her hands on his shoulders, his stomach did a series of flips because she was kissing him again, and he didn't try to hold himself back anymore, because the longer she kissed him, the more sure he became. He was probably so red that he was glowing, but Zuko didn't care, tugging at Katara's legs until she straddled him and they were full on making out in the library like a pair of desperate teenagers. In the back of his mind, Zuko knew that the librarians would be making their final rounds for the night soon, and he didn't want to be caught like this, but he felt powerless to pull himself away from her. Her grip tightened on his shoulder when he stroked her tongue with his, and impulses were taking control and there were a thousand and one things going through his mind as he broke the kiss only long enough to find new places to explore, and he'd been right about things changing between them.

When he kissed her neck, Katara showed him a new side of herself, a side that he'd had one, maybe seven, dreams about that always left him shaking and sent him to do hours of vigorous firebending practice. He kissed her again, because the sound she made sent shivers down his spine, and she had one hand entangled in his hair, keeping him at a certain spot, and the other was lightly scratching his back. His name was a breathy whisper on her lips, and never had anything excited him more than the way she moved against him when his tongue touched her. She twitched, and he could feel her, and they both froze.

"What are we doing?" Zuko whispered, using every ounce of willpower to pull away from her.

She was panting, and Zuko closed his eyes so he couldn't see the rapid rise and fall of her chest or the way she was licking her lips and smoothing her hair back. He repeated his question as he forced himself to let go of her legs as she stood and went to sit in a chair across from him. They'd moved beyond trembling and were flat out shaking.

"Maybe we should wait until our heads are clearer," Zuko said, adjusting his pants and keeping his focus on the floor.

"Right," she agreed. "Nothing good can come of hasty decisions made in the middle of the night."

"We should be responsible."

"Yes. Responsible. We've always been the responsible ones."

They looked at each other and nodded. Yes. In the morning, when their heads were clearer, they would revisit this idea. Because they were responsible adults, and that was what responsible adults did. Katara smiled at him, smoothed her robe and walked to the shelf to grab another book. Zuko watched her go for a book just out of her reach, and without hesitation, he went to help her. He smiled when she blushed, wishing his heart would stop with the rapid beating as he stood behind her, his hand resting lightly at her hip as he pulled the book down and handed it to her.

"That one, too," she said, pointing to one on the shelf above.

Zuko stepped forward, pushing her against the shelves as he reached for the book, his hand tightening on her hip just a little as she pushed into him. He closed his eyes, savoring the feeling of having her close and knowing with full certainty that he'd be awake all night thinking about her. He went for another book, pushing Katara right against the shelves, wondering if he wasn't maybe pushing things too much, because there was no way she could ignore him pressing into her. Suddenly self conscious, Zuko tried to take a step back, because they'd just said that they weren't going to do this, and he really needed to let his brain take control on this one, not his emotions. He'd probably only have one chance with Katara, and he couldn't let himself mess it up.

"I've had years to think about this," Katara said, grabbing his arm and keeping him from moving away. "And…I know how I feel about you. I know how happy I feel whenever I'm near you. I was done taking care of business here a month ago, Zuko."

"I know. I just…I didn't dare think you stayed because of me."

"I've always stayed because of you."

There weren't any words to describe just how happy that made him, and Zuko felt like laughing and crying and shouting to anyone that would listen that she stayed because of him. Smiling so wide his face hurt, Zuko spun Katara around and kissed her, loving the delighted little giggle as she wrapped her arms around his neck, and they were both giddy because this was probably really happening between them, and never had Zuko been happier about anything in his life. They stumbled back against the shelves as the giggles died away, and there were slow footsteps coming toward them, but Zuko was feeling bold and wonderful, deepening the kiss as Katara's knees buckled and she grabbed onto his waist for support, her nails digging into his sides. She pulled him closer, and he slid his hand down her back, exploring just a little, coming to rest on her bottom. Katara sighed against him, almost melting into him, and this time, Zuko found that he was the one moaning as she slid her hands under his shirt, her bare hands on his back.

"Now where did I put my list?"

It took a few moments for them to register that there was another voice in the library, let alone one that they knew. When it finally did register, Zuko and Katara sprung apart, hastily trying to fix their clothes, panic in their eyes. Zuko hoped that Katara would be more coherent than he was, because there were only two things that he could clearly think about, and his uncle's approach and how to explain their closeness were not among them. He watched Katara spin in a circle, tugging at her hair the way she always did when she was nervous, his mind starting to drift off again as she hastily shoved a stack of books in his arms.

"Oh, nephew," Iroh said as he peered into the alcove. "I didn't expect to see you still up."

Zuko blinked dumbly at his uncle, trying to find something that would sound plausible and knowing that Iroh had a unique ability to see straight through him. Even before he'd said anything, Iroh was already assessing the situation, looking at the labels on the shelves that denoted this as the romance section, clearly wondering what his nephew was doing there. Then his eyes shifted to the left where he saw Katara collecting books from the table and putting them back on the shelves, and then that stupid, sly, know it all smile slithered onto Iroh's face, and Zuko knew he had about five seconds to say something before Iroh came to his own conclusion.

"I'm helping," Zuko said hastily, trying to maintain eye contact. "I was just returning some books and saw Katara and she wanted me to get something for her."

He watched his uncle look between the two of them, then across aisle where there was a small step ladder that she could have used, then back at them.

"I did not see that there," Katara said slowly as she started to blush.

"I'm sure you didn't," Iroh said, his smile growing wider. "It is very dim over here. Not too good for reading."

"Uncle please—"

"I wouldn't want you two to strain…anything."

"I wasn't actually reading anything just yet," Katara said, stepping in front of Zuko. "I'd intended to just put these back, but I saw a few titles that caught my eye."

"I didn't think you liked these romance novels," Iroh said. "Might I suggest one of my favorites? It's called To Love in Secret, by—"

"No," Zuko cut in, grabbing Katara's arm and pulling her away from Iroh. "I'm sure she's got more than enough to read."

They could hear Iroh's soft chuckle as they quickly exited the library, closing the door behind them a little louder than they'd intended. Maybe the quick retreat wasn't the best strategy, as undoubtedly Iroh just solidified his own opinion of what was happening. It didn't matter if he was correct or not, Zuko didn't particularly want Iroh prying into his relationship this time, especially since he wasn't even sure what this relationship was.

Zuko sighed as Katara started off down the hallway, and he followed a few paces behind her. The adrenaline was finally starting to leave, and the long day was catching up with him. When he yawned, Katara looked over her shoulder at him and smiled, and it was beautiful and bright and undoubtedly happy. Zuko couldn't help smiling back, and his heart fluttered again. The day had certainly been a full one, and he let his mind drift as he looked at Katara, and how beautiful she was and how kind. How hard she worked to make the world better, and she always looked out for him and made sure that he was ok. He was so lost in thoughts of Katara that he didn't even realize when she'd stopped in front of a door. She laughed as she grabbed his arm to keep him from walking past her.

"What are you thinking about?" she asked.

Zuko blushed, shrugging and trying to look nonchalant. "Well, goodnight, I guess. I'll see you in the morning?"

"Zuko, this is your room."

Zuko looked at the giant double doors engraved with a likeness of the Fire Lord's crown. "Yes. Well. It would appear so."

They shuffled awkwardly, and Zuko handed the books over, his hand lingering on hers. Heart thudding again, he tucked a lock of hair behind her ear, then leaned in to kiss her. Katara stepped in to meet him, and Zuko put his hands on her hips, trying to remind himself of all the things he'd have to do in the morning, that they shouldn't rush into anything. But having her so close to him just felt incredibly good, and they'd both been pretty sure, right? And they could take their time and figure things out for themselves, so long as they avoided Iroh for a bit.

"Goodnight," Katara whispered, pulling away.

She turned away, but Zuko grabbed her hand, pulling her back to him, hoping he wouldn't sound foolish.

"Maybe… I mean…you're already here, you know. And it's pretty late." He shrugged. "I'd hate for you to walk all the way across the residential wing just to go to…bed."

They looked down the hallway, checking that it was empty.

"Are you sure?" Katara asked. "I wouldn't mind going to my room. I mean, if you didn't want me here."

"Do you want to stay?"

Zuko held his breath, waiting for an answer, trying not to berate himself for even asking. When she started to smile, he didn't let himself believe. When she bit her lip, Zuko fought against getting his hopes up. He didn't even let himself give in when she looked up at him through dark lashes, biting her lips and holding the books close to her chest.

"I very much want to."

He was so happy he could have passed out, and even as he opened the door and they both stepped inside, even as he closed it behind them, even as she dropped the books on a nearby table and threw her arms around him, kissing him more passionately than she had before, Zuko still couldn't believe what just happened or how lucky he was.

A/N: For Zutara Month 2015, prompts Secret Lovers and Caught mashed up and turned into a two-parter, because it was too tempting to pass up.