Author's Notes: Zuko/Katara request on Livejournal. Posted on discordent December 23rd.

Disclaimer: Standard disclaimer applies.

Summary: Post-canon. Zuko believed in a lot of things, but never ghosts. Then Katara died.

Carbon Unmade
"Time. What a stupid concept."

He believed in a lot of things – things like Gods and salvation, redemption and forgiveness. He believed in reincarnation, in fate, in destiny, in all the things he learned played an integral part in saving the world.

He never believed in ghosts, though.

Then Katara died.

—

Sokka and Hakoda had never shared all the details of what had happened, and Aang simply refused to talk to anyone, but from Zuko had gathered, a small village Katara had been staying in as a healer had been ambushed by bandits, and she'd taken a blow meant for a child.

The funeral was quiet, and the crowd was small. He tried to stay near the back, but Toph dragged him up to the tombstone at the end of the ceremony and cried into his shirt for the better part of an hour.

When they walked away, he swore he saw a flash of blue.

—

Months passed – Hakoda and Bato went between the Water Tribes, advancing the North's present technology and modernizing the South. Aang traveled more and spoke less, but at least took Toph along with him everywhere at her own insistence. Sokka and Suki stayed in Ba Sing Se, and Zuko himself spent his days trapped in a palace with only his Uncle and governed a nation. Mai had left once she realized the difference between love and desire, and he couldn't blame her. He himself had made the mistake of mixing the two, once.

He was in his study when he heard it. A light tap at the door, and the quiet swish of robes. He frowned. "Come in."

The first thing he saw was blue.

"Hi, Zuko," Katara said, her smile nervous. "Long time no see."

After that, everything changed.

—

In the days that followed Katara's… ghost's… appearance, Zuko spent a lot of time holed up in his study talking to her. Iroh never asked what he was doing in there, but he would occasionally catch his uncle shooting him worried looks. Soon, he realized, the whole palace was going to start talking and he'd be lucky if all they thought was that he was going crazy.

Which, in retrospect, he probably was, considering he was talking to a dead girl, but that wasn't the point.

She was drifting around the room, passing her fingers through everything, when he asked her, "Why did you come back?"

She paused. "I felt bad," she said to the carpet. "I just kind of… left everyone with no warning, you know? When I saw how torn up Aang was about it…" she took a deep not-breath and looked at him. "How is he doing?"

Zuko shrugged. "I haven't heard from him in weeks. His letters are sparse, these days."

She frowned the same way she used to when she was worried. Zuko felt his heart clench. "Is he… out all alone?"

"No," he replied, sifting through a pile of peace treaties that needed to be signed. "Toph pretty much bullied him into taking her along, and they've been inseparable ever since."

Katara's shoulders slumped in relief. She turned to the portrait of him and Iroh that sat on his desk and skimmed her hand over the top of the frame. "That's… good to hear."

He watched her eyes flicker from the portrait to him, the back. "She's good for him," he found himself saying, folding his hands in front of him. "He'll be okay, Katara. He just needs time."

She snorted. "Time. What a stupid concept."

He raised his eyebrows at her. "Someone's a little bitter, I see."

"Just a little," she replied honestly, but her voice was light and teasing. She met his eyes then, and the gentle lift of her lips faded. "I'm glad I got the chance to come back."

"I am, too," he told her, and when her eyes brightened, he smiled. "But you're going to have to stop stalking me everywhere – the servants are going to think I'm crazy if I keep talking to air in the hallways."

"Like they don't think that already, Mister Cooped-up-in-his-Study-all-the-time." She stuck her tongue out at him, and he grinned crookedly. "Don't give me that look, buddy. Just because I'm not corporeal doesn't mean I still can't kick your butt."

"I'd like to see you try, little girl."

Zuko later decided he probably should've kept his mouth shut when he walked into his room and found his bed soaking wet.

—

"Katara," he said, a month after she'd appeared. "Why are you here?"

She blinked, sighed. "I already told you, Sparky. The Spirits saw how upset Aang was when I died, and decided to give me some time to… give him closure. I can't do that until he comes back from wherever he is, though."

"That's not what I meant," Zuko said, leaning back in his chair. "I meant: why are you here," he gestured around them, "in this palace, with me?"

She stood in front of his desk and stared guiltily out the window. "Dad's really busy," she said, almost sadly. "And Sokka… Sokka has a whole new life now, with Suki and the baby. I just… I didn't want to upset them by showing up suddenly, still dead but walking around anyway. Not when they have so much going on already."

"So you came to me?" Zuko cocked his head to the side. "I'm Fire Lord, Katara. Don't I have a lot going on, too?"

She jerked towards him and bit her lip, eyes narrowed. "Do you not want me here?"

Zuko spluttered. "That's not what I – I just meant, everyone's busy, so why come to me, the guy you used to hate?"

"I don't know!" she huffed, and stomped her foot – though it only went through the ground. "I just did, okay?"

He blinked. "Okay."

She went back to staring out the window. "Okay."

—

One night, he was staring at the turtleduck pond, and she said to him, "I was with Aang because I felt obligated to keep him happy. He's like a little brother to me, but he's the Avatar too, and if I rejected him…"

"You thought the world would blow up?" Zuko supplied, swirling his fingers in the water.

Katara nodded. "Yeah, pretty much."

He snorted a laugh. "That's funny," he went, half-smiling at his own reflection. The scar scrunched up on the side and his eye disappeared behind mottled pink skin. "I thought the same thing about Mai."

Katara giggled into her transparent hand. "I… can understand that."

"Yeah." He frowned. "But, irony of ironies, she's the one who ended up leaving me."

Katara stopped laughing. "Zuko…"

"It's okay," he said, and he meant it. "My world didn't end like I thought it would."

She was quiet for a long time after that. The two of them sat and stared at the moon and the stars, and Zuko forced himself not to look at her whenever a servant walked by. Eventually, as the wind picked up a little, she said, "Do you think things could've been different, if you'd joined us in Ba Sing Se?"

Zuko winced. He generally tried not to think about Ba Sing Se, if only so he wouldn't have to remember the look of utter loathing she'd shot him when she'd realized he wasn't coming with her. "Yeah," he replied. "We probably could've taken my father out on the day of the eclipse, if I had."

"No, I mean –" she hesitated, lips thin. "I mean… between us. Do you think things could've been different… between us?"

He looked at her hard for a very long time. When she started to squirm, he exhaled through his nose. "You know," he went, turning to the pond again. "I never regretted being alive, not even when I was banished."

"Zuko, what does this have to do with –"

"I've never regretted being alive," he said, cutting her off. "But right here, right now, sitting next to you and knowing you're only a spirit… it makes me wish I were one, too."

"Don't say that," she whispered, fingers curling into her dress. "Please don't say that."

He scowled. "Why?"

She was almost shaking, knuckles white as she clutched her necklace. "Because it might just come true."

—

A week later, someone broke into the palace and tried to kill him.

"I told you," she said, while he cleaned up bits of broken vase and had a servant find someone to fix his window. "I told you not to wish you were dead, and now someone up there's heard you and—"

"Someone in the Spirit World wants me dead?" he said dryly. "Why am I not surprised?"

"This isn't funny, Zuko!" she snapped, and for just a second, her hand touched his arm. He whirled on her, and she looked just a stunned as he did. "I… uhm…"

"You… can touch me?" He stepped closer to her. "Do it again."

Her fingers pressed against his bicep and stayed there for a few seconds before passing through. Her lips parted in surprise. "I… It doesn't last for very long, though."

"Doesn't matter," he said, and kissed her.

—

Everything was quiet again for a few days, and then, on the night of the full moon, someone broke in again.

The next morning, she stood next to him and sighed. "I told you s –"

"You can't say that," he told her, fingers brushing hers quickly. The bed was a mess of wrinkled sheets and tiny flecks of blood from the scuffle. "You said that the first time, remember?"

She pouted and crossed her arms over her chest, turning away from him. "Whatever. When's Aang coming back?"

Zuko ran a hand through his hair and shrugged. "His last letter said he'd be stopping by in a few days, though I suppose with everything's that's happened he'll be coming back a bit sooner. He doesn't seem to like it when people try to kill the Fire Lord."

"I wonder why," she deadpanned. She moved back to him and squeezed his hand lightly. "Let's go for a walk. Your room is really quite boring, you know."

He shrugged again and motioned towards the screen doors leading outside. "Alright. I'll show you the turtleducks – I don't think you've ever seen them, since we only go outside at night."

She smiled brightly at him. "I'd like that."

Together, they walked towards the garden, and as Zuko closed the screen door behind him, he looked at the bed and snorted.

"I don't regret living," he said quietly, and mostly to himself. Katara called his name from somewhere across the garden, near the tree he used to sit underneath with his mother. Sunlight filtered through her transparent shape, and he smiled. "But I don't regret dying, either."