Here's a reminder of who know what:

Zuko - Fire (Master), Air (some), Water (some/healing)
Katara - Water (Master/Healing), Earth (Some/Limited seismic-sense), Fire (some)
Toph - Earth (Master/The best in the world/Metalbending), Fire (beginner/Heat-sense)
Sokka - None, Sword

Sokka drifted from blissful unconsciousness to fuzzy awareness. His first clear thought was, I'm alive?

The second was a realization that he didn't hurt very much anymore.

His third was that he was warm. Warm, with the familiar comfort of sleeping bodies curled up next to him. It was how things were done in the Water Tribe. Everyone piled together in the cold dark months.

It was dark. So dark he couldn't see his hand in front of his face, but he knew Katara slept on one side of him. The extra toasty warmth and bony elbow digging into his ribs on the other side had to be Zuko. The small but very heavy weight across his legs was Toph.

I'm alive. They got me out.

Of course they did, he thought fuzzily, sliding back down into sleep. They're Avatars.

His dreams that morning were of strange, huge animals he had never seen before. Like big furry sea-cows who used their big flat tails to fly through the air. Sokka rode on one and used his staff to herd them quietly along to a new pasture visible as a strip of green just over the horizon.

He woke a second time, later that afternoon to his sister haranguing Toph.

"Toph! Why are you asleep? You were supposed to be on the lookout!"

"Relax, Sugarqueen. I would have felt anyone coming a mile away. They'll be digging themselves out of that fort for days."

Katara growled and there was a sudden rumble of stone above them. A square hole opened way above their head. Sunlight poured in and Sokka realized they were all sleeping encased in a large granite dome in the middle of the forest.

Sitting up, he looked around and spotted Toph, first. The littlest Avatar had a hilariously bushy bed head. Sokka would have pointed and laughed, but the arrow wound under his collarbone made itself known and... yowza. That hurt.

Weirdly, the one in his stomach seemed good as new. Just a weird puckered scar for his trouble. Like a second belly button.

He poked it and got a twinge again for his collarbone.

"Stop that," Katara snapped. She made him lay down and wielded a blue-glowing glove of water at him like a weapon. "Zuko, wake up. This is a healing lesson."

Zuko made a weird groan, but dragged himself awake. His bedhead was almost as bad as Toph's. He looked like living death, his skin parchment paper white.

"Uh... is he okay?" Sokka asked.

"He's learning the dangers of a healer overextending himself," Katara said in a very sweet tone that made all of Sokka's warning bells go off.

"Wait..." Several memories came together in his mind. "Zuko healed me?"

"Yup," Toph said, popping the 'p'. "Katara was busy fighting her first Agni Kai."

"You won?" Zuko's voice was gravel and he not so subtly moved into the beam of light cast down by the dome's skylight.

"What do you mean, first Agni Kai?" Sokka grumped. Naturally, the others ignored him.

Katara flushed and ducked her head.

Toph grinned. "She whooped Zhao so hard his ancestors will feel it," Toph said.

"Nice," Sokka said, making himself relax. His sister had come out unburnt, after all. "I wish I saw that. He was a dick."

"You have no idea," Katara said with feeling and pressed the globe of water to the spot on Sokka's aching chest.

She talked to Zuko, explaining her method as she healed him. Sokka didn't get much out of it-blah, blah, blah, bender stuff, blah-but understood that normally healings were done in small sessions, not all at once-AHEM ZUKO. That explained why his stomach wound was as good as new.

"How long until I'm fighting fit?" Sokka asked as she pulled her hand away. He rolled his shoulder experimentally. Still a sore, but a lot better.

Katara considered for a moment. "Three more sessions at least."

"Okay. So what aren't you telling me?"

He got great satisfaction from his sister's shocked expression. Her glowing glove of water actually wavered.

"Wh-what?" She tried to laugh it off, high and light and completely fake.

"That is a fake laugh. I taught you that laugh," he said. "Spill."

"Fine." She put her bending water away back in her pouch. "There might have been something I've been… keeping to myself. When we discovered you were kidnapped, I got upset."

Toph snorted.. "Understatement,"

"When you went into the Avatar state?" A few minutes in direct sunlight seemed to have done Zuko some good. He looked more alert. Worried, even.

"The Avatar what-now?" Sokka asked.

"It's when the Avatar spirit comes to the front. It's... dramatic. You'll know it when you see it," Zuko explained.

"While I was there, I had a vision..." And Katara went on to explain a truly bizarre tale of a land of mist, of a line of Avatars, and seeing herself in an Earthbender's body. "Then I—he—told me, 'This has happened before'."

"This has happened before?" Sokka repeated. "When?"

She shrugged. "I don't know. I woke up and then... I had to find you.'

They were silent and dumbfounded.

"Well that's just great." Toph threw her hands up in the air. "I don't suppose your past life could have been more helpful?"

"You could go into the Avatar state next," Katara said snippily. "Tell us what you see."

"I'm just saying. I'm getting tired of more questions. I'd like some answers."

"This has happened before," Zuko repeated, slowly. "This has happened before... Then shouldn't there be some records? An Avatar disappearing and more taking his place?" He looked around and received shrugs.

"It was way down the line," Katara said. "Centuries, maybe thousands of years ago if they all lived to be two-hundred like Kyoshi."

"The Dragon Bone Catacombs might have records going back that far." Zuko's shoulders slumped. "Too bad it's in the Fire Nation."

There was a lull as everyone processed that. In the spirit of oversharing, Sokka thought it was time he spoke up.

"So," Sokka said. "I think I remember Aang."

All activity stopped. Sokka tried a grin, but it came out as a grimace. "Short kid, right? Eleven or twelve with Airbender tattoos and ears that stuck out a little?"

Katara put her hand over her mouth, her eyes suspiciously bright. Toph shrugged—overall looks obviously not being her area of expertise.

Zuko, though nodded. "That's him. What do you remember? How do you remember?"

Sokka shrugged. "One of the Fire Nation guys gave me poppy milk tea. The next thing I know, I was talking to this kid."

"In the spirit world?" Katara asked.

"No, that's the thing. It was like a memory… only weird. More real." He looked around at them. "Were we ever at the Southern Air Temple?"

"Yes!" Katara said, jumping to her feet in her excitement. "That was one of our first stops after leaving the South Pole. Aang wanted to go there because he used to live there and he… had to make sure all the monks were gone."

Toph stretched out, cracking all her toes in unison. "That was before my time."

"Me too," Zuko added.

Sokka squinted, thinking back. "That sounds about right. Aang looked really upset. I remember thinking that everyone had put too much weight on his shoulders. Like… they expected too much from him? He was just a kid."

"He was upset," Katara said quietly. "Especially right after… well, he found his guardian's skeleton."

"Ouch. I don't remember that part." But Sokka was grinning. It was awesome to finally remember something out of the other lifetime. Better yet, it was something that Zuko and Toph didn't know. "I saw that he was kind of blue, and told him everything was going to be all right."

"That… sounds right." Though Katara seemed hesitant.

Sokka, though, was on a roll. "And then I gave him a couple of fruit pies."

"Er, no," she said.

"Yeah, I did! I totally stole them from the kitchens."

She put her hands on her hips. "Sokka, the place was a graveyard. I would have remembered if you fed Aang one-hundred-year old pies."

He threw his hands in the air. "Well, I didn't see you weren't around. I must have snuck them somehow in my giant sleeves." He pulled at his own short-sleeved blue tunic, expressively.

"How much poppy juice was in that tea?" Toph asked. Katara laughed.

Zuko, though, had a slightly constipated look on his face. "What season did you visit the temple?"

"Winter," Katara said.

"No, it was summer, because the cherry-beet trees were in bloom," Sokka corrected firmly.

"Poppy-juice," Toph sing-singed.

Zuko's eyes went wide, then narrowed in thought. Sokka turned to him. "What?"

"Nothing." He scowled then hesitated. "It's just… I've heard of something like this, in Fire Temple Teachings. But I don't know if it applies… um, here."

"What, about poppy juice?"

"Not… exactly."

"Zuko, what is it?" Katara asked.

Again, he hesitated. "It's one of the few decrees Fire Lord Sozin issued that I agree with. Back in his time, some of the more… extreme Fire Sages used to intentionally poison themselves to the brink of death. He outlawed the practice." He snorted. "Actually, it was his most controversial decree… um, before the comet. The Fire Sages argued it was a religious right. It was said Avatar Roku sided with them and publicly chastised Sozin for it. But Sozin refused to rescind his decree. It still stands to this day."

Sokka and Katara exchanged a bewildered look.

Toph spoke their confusion for them. "Okay, but why were the Fire Sages poisoning themselves?"

"Oh. Right." Zuko seemed to shake himself out of his historical musings. "Because they believed when they were on the edge of death they would sometimes receive memories from their past lives."

"Hello," Sokka said. "That's what I'm saying happened."

"No," Zuko said firmly. "Not original Sokka's life… The life you had before that." Again he hesitated and added, almost gently—for him. "Air comes before water."

Silence.

"Wait," Toph said, sitting straight up. "Wait, are you saying what I think you're saying?"

"It was a summer's day at the Southern Air Temple where Sokka remembers giving Aang fruit pies that haven't existed for a hundred years," Zuko said. "I'm not saying Sokka's brain wasn't fried by poppy juice, but considering how Katara saw her past life in the Avatar spirit mist… It sort of makes sense."

"No, it doesn't!" Sokka had a bad feeling he should have kept his big mouth shut. And he wasn't mentioning a word about his dreams, either.

"Sokka remembers speaking to Aang people were living in the Air Temples," Katara repeated slowly as if trying to fit two puzzle pieces together. "And… myself, Zuko, and Toph were all Aang's bending teachers, and we came back…"

"Who was Aang's airbending teacher?" Zuko asked.

"His guardian, Monk Gyatso. He was supposed to be the best airbender in the world."

Katara and Zuko turned to stare at Sokka. Even Toph, in her own way. Sokka did not like this. Not one bit.

"Look, if I was this Monk Gyatso guy from the past then wouldn't I have memories, too?"

"I think that's exactly what you saw," Zuko said. "One of his memories, of Aang."

"I meant why didn't I go back to the age of twelve years old, as him?" He waved his arms in a parody of bending. "With all the cool Avatar powers?"

Katara answered for him. "Because Monk Gyatso died when the Fire Nation killed the rest of the airbenders during Sozin's comet. His spirit had already reincarnated… into you, Sokka, who wasn't one of Aang's bending teachers."

"Why? Because Aang already mastered air?" Toph asked.

"That would be my guess," Zuko said.

Sokka opened and closed his mouth several times, trying and failing up come up with a denial. "This is stupid. No." He crossed his arms. "Nope. N-O."

"Even if Sokka used to be Gyatso, what does it matter?" Toph asked bluntly.

Katara and Zuko looked at each other again, then mutually shrugged.

"I don't know," Zuko said. "Maybe it doesn't matter at all, but it explains why the three of us came back and original Sokka… didn't."

Sokka was still in complaining mode. "Why couldn't I get better a better memory?" he whined. "Maybe about that Suki girl. Do you think we ever kissed?"

"I think you did more then that…" Toph smirked.

"Oh man. And all I remember are stupid fruit pies? Unfair."

Zuko pinched the bridge of his nose. "Anyway, I have something to tell you all, too. I ran into Jeong-Jeong at the fort."

"I saw him too!" Katara exclaimed. Toph nodded.

"Yeah, he's the guy who gave me the memory-bending juice," Sokka said. "What about him?"

"He's not supposed to be there. He's supposed to be half a continent away living as a hermit."

"He was Aang's first firebending teacher," Katara said.

"All he taught him was to fear fire," Zuko growled, then admitted. "But Jeong-Jeong didn't seem to remember me from… before." Then he went on to briefly outline their conversation and produced a lotus tile.

"So… what changed? Why is he here now?" Toph asked.

"No idea," Zuko admitted.

"He had deserted the Fire Nation the first time. Why did he do that?"

Zuko squinted, thinking back. "I think it happened right after my banishment. I… Well, if it didn't directly involve rumors of where the Avatar was hiding, I didn't pay a lot of attention."

"Big surprise." But Katara elbowed Zuko in the ribs to take the sting out of her words.

"A little obsessed over finding the Avatar, huh?" Sokka asked.

She grinned back. "You have no idea."

"And I did find him," Zuko said, "And now I think I need to find my Uncle."

"The Fire Lord's big brother?" Sokka asked. "Why?"

Zuko pinched the bridge of his nose. "He's not like my father. And like Toph said, we need some answers. And I need to make sure he's okay."

They all exchanged glances.

"He is pretty wise," Katara admitted.

Again, Zuko showed around the White Lotus tile. "He has connections with other grand masters who might know what's going on."

"Do you know where he is?" Toph asked.

"Maybe Ba Sing Se?" Zuko guessed. "He was really happy running his tea shop."

Sokka felt his stomach drop. "I think… we'd better head to Omashu."

Katara was studying him hard, and curse her sisterly instincts because she said, "Sokka? What happened?"

"Welllll…" There was no way he could make this sound better than it was. "Zhao wanted to know where 'The Avatar' was," he said with air quotes. "And I had to make something up. Omashu was the first place I could think of." And he had just painted a big fat target on it for the Fire Nation.

Katara gripped his hand and by the anger simmering in her blue eyes, she had read between the lines and knew why Sokka had become so chatty. Even Toph looked grim. Zuko, typically, didn't get it. For a supposed prince he took a lot at face value.

"King Bumi is a member of the White Lotus," he said. "It's a good place to start."

Katara squeezed Sokka's hand and then let go. "Fine," she said crisply, "But if King Bumi challenges us, I am not being bait for Flopsy or challenging a hundred and twelve-year-old man to a duel or getting imprisoned by rock candy Genemite. I'm calling it right now. Not. It."

"Not it," Toph echoed, while Zuko looked on, bemused.

"Not it," Sokka repeated, more by rote than anything else. Then his brain caught up with the rest of what his sister had said. "Wait, what?"

Notes:

I'm sure their trip to Omashu will go exactly as planned. :)