Aang hadn't thought about that day in a long time.

He avoided thinking about it actually. There were so many things about that day that were painful. Which was probably why he'd been so disconcerted to have it invade his dreams this morning. He'd tried to brush it off, determined not to let those memories ruin his today. Especially not today. Today was supposed to be a happy day. That's what Katara always said.

But now, as he watched the sun set, Aang was starting to realize why that day and the bargain he had made was weighing so heavily on him.

Slim arms reached around him and pulled him out of his thoughts.

"You've been somewhere else all day," Katara said. The hard bones of her cheek and brow, no longer cushioned as they had once been, pressed against his back. He separated her hands, bringing her around to his side so she could watch the display of red and orange and gold with him.

"Just…thinking," Aang said.

Katara smiled. "You would ruin a perfectly good birthday by thinking." She slid a hand up his chest, letting it rest over the comforting beat of his heart. "Happy birthday, dear."

Age had been far kinder to his wife than it had been to him. The lines of her face were softer and fewer than those he bore. But they were both still strong and for that he was thankful. That made his bargain all the more cruel. He had no doubt that she would outlive him for many years to come.

It would be soon. That he knew. Not from any physical failing, it was just a feeling deep inside him.

"Katara," he started. He let out a sigh. Did he warn her of the knowledge that grew steadily within him? Or did he let her live the rest of their days together in ignorance? What would Katara want?

"It's alright, Aang," she said. Her eyes searched his, still bright and clear as the day he met her. "You can tell me." Her smile still made his heart stop.

He reached up to brush the hair away from her face, his fingers trailing into her salt and pepper tresses. She'd left it down today, because she knew he liked it down. Gently, his fingers traced behind her ear, down the line of her jaw. The skin was soft against his calloused fingers. He turned his eyes to the skyline.

"I…do not think I will see sixty-seven," he said. The gentle movement of her breathing stilled for a moment. Then she sighed.

"Do you feel…unwell?" Now it was Katara's turn to focus on the horizon.

"No," Aang said. "I just sense that my time as avatar is coming to a close." He felt her face press against his chest as her arms wrapped around him. He looked down, but her face was obscured by the top of her head. "Katara?"

"I'm…alright," Katara whispered after too many minutes of silence.

"I'm sorry to burden you with this. I just…want you to be prepared…"

"Aang, it's fine." She looked up at him now, both her hands coming up to cradle his face. He could see the tears lining her eyes. "I have said goodbye to you every night since that day, thoroughly expecting you to be gone by morning." One hand came away from his face to wipe at her eyes. Aang grabbed it and pressed it to his cheek again. "We have had a good life," she said. Her voice was soft. Aang closed his eyes. He felt as she rose to her tiptoes, pressing her face close to his. "I have been thankful for every day with you, but I've never forgotten that our time is borrowed." She laughed softly. "We've had too many brushes with death to forget that."

"I will wait for you," he whispered. "Just as I waited for you in that iceberg."

Katara laughed again.

"Then make sure you get comfortable. You may remember, I have to wait until our third great-grandchild is born."

Aang laughed too, his arms encircling his wife. She always was the strong one. He wouldn't have asked his next question if he hadn't been completely confident in her strength.

"Katara, the next avatar will be a waterbender," he began. He put some distance between them. Her reaction was something he wanted to be able to judge. "Will you…could you teach him?" Aang swallowed. Had their positions been reversed, he wasn't sure he would have been able to do that.

"Or her. The next avatar could be a girl."

"Or her."

Katara pulled him down for a kiss. "Yes, Love. I'll teach him or her. After all, how many people get the chance to teach two avatars?"

###

It took many years for that third great-grandchild to make its appearance. But Katara had learned patience many years ago as a young mother. In fact, she was sometimes convinced that Bumi had been born with the sole purpose of teaching her patience. When she was young, twenty-five years might have seemed like a lifetime of waiting, but it passed quickly now that she had reached the latter part of her life.

Of course, that didn't mean she did not still ache for the company of her husband. But he had made a promise, and Aang had always been especially good at keeping his promises. It was with joy that she embraced her second trip into the spirit world. She knew that there was no coming back this time.

The air around her wasn't as dank and humid as it had been all those years ago. It was still swampy, but more open and less threatening. Sunlight filtered down to sparkle on the wet earth. Katara took a step forward, the spongy ground sticking slightly to her feet. The ease with which her legs moved caused her to examine herself. Her limbs, she found, were smooth and supple and young again.

"That's the wrong way," a voice came.

Katara felt a jolt of electricity flash down her spine. If she had been alive, she would have stopped breathing. Spinning, she faced the direction of her husband's voice.

"Aang," she breathed.

He was there, pretending to lean casually against a well-endowed tree. He too had regressed to point before time and stress and children had aged him. His simple airbender's robes clothed him. But even the flowing lines of his garments could not hide the tension. Katara could tell that Aang was wound like a spring, ready to flow into action at just the right moment.

This moment.

With a yell, Katara ran for Aang, not even taking time to revel in the ease of movement that had eluded her for years. Aang was ready to meet her. But he only got a few steps in before her feet left the ground and she jumped into him, arms and legs wrapping around his young man's frame. He caught her, arms circling her waist, holding her up.

"I missed you," she whispered. One of Aang's hands brushed against her cheek and up to her ear before losing itself in her hair. Blue eyes and grey held each other. A thousand thoughts passed between them.

"And I missed you. So much."

Katara closed her eyes. His mouth brushed against hers. Once. Twice. She felt her world shift. Felt the rough bark of the tree through the thin material of her shirt. She uncrossed her legs, letting herself slide down until she was standing on his feet. Her hands found his.

The kiss was far shorter than she expected. Or wanted. After so many years, she wasn't sure she ever wanted it to end. Aang stepped away, but not far, his fingers still twined with hers. Katara found herself leaning into the space where he had been.

"Now what," she breathed.

Aang grinned.

"There's so much I have to show you. So much to do. But first…" His eyes winked at her.

Katara's own mouth mirrored his mischievous smile. "But first?"

Aang placed one hand against the tree and leaned closer.

"But first, how about somewhere with a little more privacy." His breath brushed over her eyelids and cheekbones. She smiled.

"Mmm, privacy sounds good."

He stepped away, giving a playful tug of Katara's hand. She stepped forward and found herself facing the sky, Aang's knee pressing sturdily into her back.

"Welcome to forever, Forever Girl." His kissed her and quickly pulled away. Setting her back on her feet, Aang led her deeper into the jungle.

Katara was looking forward to forever.

So LoK has reignited my ATLA obsession (which really means my Kataang obsession) and I've spent the last week scrolling through the Avatar fanfiction (again read: Kataang). I've found some really good stuff. But one thing that keeps bugging me is this idea of Aang wasting away and then Katara wallowing until Korra shows up. And I'm like "AAAAHHH! OOC!" I dunno, I just had this idea in my head of Aang passing peacefully in his sleep when his body was just done...So that's what I wrote. Love it. Hate it. I don't care. Just skip the ship war crap, because in the end the only people who really have any say over that are Bryke.