A/N: Originally posted on tumblr, where it was written as a birthday fic for taliaxlatia. They asked for something in the ATLA Role Reversal AU, where it's the Water Tribe, not the Fire Nation, that is after the Avatar. Specifically, they asked for the point where Sokka wants to join the Gaang. Standard disclaimers apply.

"We're not alone," Toph said, stopping in her tracks and nearly causing Zuko to bowl into her.

"What's that supposed to mean?" Azula said sharply, and Toph pointed a finger at the wall of rock ahead of them. Azula had thought they were safely within the Earth Nation, far from any patrols the Water Tribe might have sent out. They were walking now to give Appa a break from flying, but they weren't on known trade routes; they were specifically avoiding the paths on any map she'd ever seen. As far as she could tell, they were a day's walk from the nearest village, but—

"There's someone in there."

"Inside the cliff?"

"We're in the Earth Kingdom. It's not just a cliff. Someone built rooms inside. I'd guess it's a bunker if we weren't so far from the old front lines."

"So someone's home? Whoever built this place?"

"Maybe. Or maybe it's abandoned and we're not the only visitors."

Azula looked at Aang. "We can't risk the Water Tribe finding you. Zuko can check it out."

"Hey!"

"Don't hey me," Azula shot back. "If they've sent that crazy old blood bender after us again, you're going to need my lightning to neutralize her. Unless you've suddenly figured out how to do it?"

"Crazy old blood bender?" Toph repeated. "What happened to you guys?"

"It's…kinda a long story," Aang said, the apology in his tone, but Zuko snorted and contradicted him.

"It's really not. Her name's Hama, and we think she's the one who taught Katara to blood bend. It's exactly what it sounds like. She can turn you into a living puppet. We're lucky she didn't kill us all the first time."

"Uh, guys?" Toph interjected, but Azula wasn't going to let Zuko leave it at that.

She sniffed. "I wasn't with Zuko and Aang when she ambushed us, which gave me the opportunity to catch her by surprise, and the old hag is as susceptible to lightning as everyone else." She turned back to Zuko. "Which is why you need to investigate."

"Because I'm suddenly the most disposable?"

"Guys!" Toph stamped her foot, and the rock in front of them split. She pointed ahead of them again.

Azula followed her finger, and her heart jumped into her throat. She moved in front of Aang, knew Zuko was doing the same to guard his other flank, and both of them readied themselves to fight.

"It's okay," Aang said. "He's alone. Right, Toph?"

"Right."

"I'm not here to hurt you," Sokka said, sounding remarkably put together for someone who'd just fallen through a window that had once been a wall of rock. Azula supposed it said something about his composure, about his upbringing, the way he simply stood up and dusted himself off as if it were nothing, but she hated him for it. And I'm not here to hurt you? Azula nearly sent a lightning bolt at him for daring to presume that they'd fall for a trick like that after everything they'd been through.

"Sure," she bit out. "Of course you aren't. Because you've never tried to kill or capture us before. That was someone else, like your crazy sister."

"Katara's not…. Well, she wasn't always. But I'm not here to make excuses for her or for me. I'm sorry for everything I've done, and I want to make up for it." He hesitated. Another acting job. She kept her anger under control, ready to let it lash out all at once. "I…I came to join you, if you'll have me."

"We won't," Zuko said flatly before she could open her mouth. "Now how did you find us?"

"Consider it a show of good faith," Azula snarled when Sokka didn't immediately volunteer the answer.

"I was guessing," Sokka started, and she sent a small burst of flame past his shoulder—a warning shot, and it was with some satisfaction that he flinched away.

"Try again," she ground out.

"Look, I…. I know what you're doing. I know you're trying to get in touch with sympathizers in the Earth Kingdom to get enough supplies for the next leg of your journey. I know you're making your way to the southernmost peninsula before you set off over the water—"

"So that's where your sister plans to ambush us?"

"Azula," Aang said quietly, "let him talk." He glanced at Toph and added, "There still isn't anyone else around, Toph?"

"Just us. He really did come alone. I think he fell in through the chimney, too." A grin grew across her face. "Unless you got yourself stuck inside on purpose?"

Sokka's answering smile was sheepish, and Azula didn't trust it for a second. "I was rigging something up. I would've gotten out soon."

More likely, he was strategizing and trying to catch them unawares. She still couldn't believe he'd found them. They'd been so careful not to leave a trail. It's another reason they weren't flying everywhere they could, even though they'd be able to cover more ground that way. So what wasn't he telling them?

Before Azula could say any of this, Aang had stepped forward and was gently nudging her and Zuko to the side. "Why do you want to join us?"

Sokka picked at the wrapping around his left wrist for a few seconds, not meeting their gaze, before finally whispering, "Because I don't think I'm on the right side of things."

"Well, you aren't," Azula spat.

Aang put a hand on her arm, and she bristled but quieted. "Go on," he prompted.

"Life was always…hard," Sokka said, ignoring Azula's snort and Zuko's bark of laughter. Instead, he raised his eyes to meet Aang's. "Katara is strong, the strongest water bender in our tribe to be born for generations, but the expectations placed on us, her especially, are unachievable. She's never seen to be as good as she needs to be, so she keeps working, and she gets better. You won't be able to beat her without help. Especially not if you come to fight her on her own turf."

Azula couldn't keep quiet anymore. Did he think they were idiots, that their planning was for nothing? She wasn't about to tell him their plan, of course, but he really didn't think anything of them if he thought they were going into this without any sort of plan. "Because she'll just turn us into puppets and kill Aang when he can't move to defend himself?"

"Katara can only blood bend under the full moon. She's good, but she still needs to be at her strongest to do that."

Azula blinked. They hadn't realized that. Sure, Hama had ambushed them at night, and it had been a full moon then, but they'd assumed she'd struck at night to try to catch them off guard. They'd assumed she'd wanted the moonlight not just for the strength it gave her but for the light it would give her to move around. If she hadn't had that argument with Zuko, if she'd been in camp with the rest of them….

"I can help you," insisted Sokka. "Aang, you still need to learn how to water bend, don't you?"

"You're a non bender," Zuko said. "How can you teach water bending?"

Sokka crossed his arms. "I know the forms."

"Bending is about more than just forms," Azula snapped. "Not that I'd expect you to know that. It's about feeling and intention as much as it is form."

"And I sat through the same classes as Katara when we were younger," Sokka countered, "and watched more even after it was clear I wasn't a water bender. I can teach Aang if he'll have me."

"You should give him a chance," Toph said quietly. "You need a water bending teacher, and we can't afford to be picky."

"We can't afford to trust him, either," grumbled Azula, "after what he's done to us."

"I don't expect you to trust me," Sokka said. "I'm only asking that you give me a chance to atone. How much do you really know about the Water Tribes? Do you know anything about our strategies? Our weaknesses? You don't even look like you could make it through our defences. You don't need to worry about Katara if you can't make it that far."

"We're not telling you what we know," Zuko said. "How stupid do you think we are? We're not going to—"

"We don't need to tell him our plans before we find out everything he has to offer," Toph interrupted, "but you two don't need to keep shutting him down before we—or at least Aang—hears him out. This isn't an ambush. I'd know. He's alone. And if he found us this time, he could find us again even if we try to leave him behind."

"I can't believe you're going along with this!" Azula exclaimed, throwing up her hands and hoping Toph had half an idea of how much she was glaring at her right now.

"I'd say I can't believe you're not letting Aang have a say in this when he's the Avatar, but you're you, so that would be a lie."

"Toph!"

"Toph's right, Azula," Aang said. "I need a water bending teacher."

"Your water bending teacher should actually be a water bender." Azula saw Sokka flinch at her words, but she didn't care. So what if that was a sore point for him? It was the truth.

And for a non bender, he was dangerous.

Something Toph and Aang seemed to be forgetting.

That boomerang of his wasn't just for show. He could use it and use it well, potentially incapacitating a bender who didn't see his attack. She had never let him get close enough to get into any hand to hand, but she didn't doubt his combat skills on that front, either. For all she knew, he was as good as Ty Lee, or nearly so.

And trusting him just seemed to be such a phenomenally bad idea.

Aang was too soft, too trusting, and she couldn't let him make this mistake. She turned her head slightly to find Zuko already looking at her. He gave a slight nod, his lips pressed tight in an expression with which she was painfully familiar. He was ready to fight, just as she was.

They'd have to separate Sokka from that boomerang of his first. She didn't want to doubt Toph's skills after what she'd seen her do, but Azula wasn't going to risk Sokka taking out their earth bender. Aang was pretty good now, but Toph was far better. Azula didn't plan to sacrifice any of her friends, but the truth of the matter was, she and Zuko were more expendable than Toph. There were two of them, and if they had to, one of them could see Aang through this. He didn't have to have two fire benders by his side.

She shifted her weight to adjust her form and saw Zuko mirroring her. Sokka noticed but was too late to react. And by the time the cry of protest left Aang's lips, fire and lighting were already racing towards the relentless hunter who'd dogged their steps for so long.

If he wanted to come along, well, he could do that as their prisoner—their hostage—instead of as their friend.

It might have worked if the earth hadn't suddenly closed around Sokka, protecting him, while simultaneously swallowing her and Zuko until they were up to their armpits in sand.

"I'm calling a time out," Toph said as the earth around Sokka shifted, freeing his face but still trapping the rest of him. "Aang, you can let these guys out once you have your answers. I'm going to get some water. See if you can figure this out while I'm gone."

Struggling got her nowhere. "Toph! This isn't funny!"

"Neither is frying people we need on principle." Toph raised one hand in a wave as she walked past. "Have fun."

"Aang, are you going to get us out of here?"

Aang shifted on his feet. "Um, soon, but maybe, ah, Toph has a point. About talking. And I really do need a water bending teacher."

"I can't believe this," Azula muttered, except that wasn't true. She could believe it. This was Aang, after all. Even after everything Sokka had done to them, Aang would be willing to give him another chance. That's just the way he was.

Whether she liked it or not, Sokka was going to be Aang's water bending teacher. And she and Zuko might not trust Sokka as far as they could throw him, but if he was going to join them, at least she could count on her brother to have her back—and have an extra set of eyes on Aang's, just in case.