Aang was glad his Masters were also his best friends.

Toph was uncompromising and impossible to impress. Zuko was determined and disciplined. They kept him humble. And Katara, well, he was pretty sure Katara was trying to kill him.

He turned away from a water whip that missed his shoulder by inches and threw out a shield of ice that he knew would buy him no time. He expected her to come through it, straight on, but instead she dodged around the side, toward his back, having noted the direction he pivoted to avoid her last attack. She sent another whip at him and he ducked. In the split second he wasn't looking at her, he felt her move around toward his back again, the vibrations through the stone floor and sloshing of water giving her away. He spun to face her as he righted himself but lifted one of his heels to do it. She'd been watching for this and he felt a tentacle of water snake around his ankle - the one belonging to the only foot securely planted on the floor - before she yanked it out from under him.

Before he could hit the stone, Katara froze the water around him as he splashed through it. He reacted quickly enough to melt it but then she was standing over him, the point of an ice blade inches from his face.

"Woah," he said, holding up his hands, "Mercy."

Katara held back a triumphant smile - poorly - and let the ice melt. He squeezed his eyes shut as the water splashed down into his face. He opened them again with a gasp of mock indignantion. She laughed and held out a hand to help him up.

"You're scary sometimes," he said, as he stood. He bent himself dry and she grinned.

"I feel good today," she said with a shrug.

"You look good," he affirmed. "The hand to hand training you've been doing with Sokka and your dad really shows."

"Thanks," she said, squeezing the water out of her hair, "You guys are spoiling me. I figured I better get in a few good rounds before I go."

He sighed and pulled her into his arms, pressing a kiss to her forehead. "I'm going to miss you," he murmured. She locked her arms around his waist and squeezed him as tightly as she could.

"I'll miss you, too. I wish you could stay longer than a day." She hesitated, "I'm nervous."

Katara had been invited North to teach. It was the first time a woman would be formally teaching combat and she would be working alongside Pakku. Aang was preparing to receive visitors to the Southern Air Temple, first the Acolytes, then a group of architects who were working on the restoration, so he couldn't stay long.

"You're going to be great," he said. He released her to look into her eyes, "You're an amazing teacher."

She sighed, hugging herself, "I just know Pakku's going to be scrutinizing everything I do. I thought he might let up a little after he married Gran but I think he's actually gotten worse."

"Yeah, I noticed last time we were South," Aang agreed, "I mean, you're his granddaughter now. He can't let it look like he's taking it easy on you. He's proud of you, though. He smiles at you when he thinks no one's looking." This tugged a reluctant smile out of her and he went on, "Plus, think about how excited those girls are going to be to learn to fight from you. It's going to be so inspiring for them."

Her gaze dropped away from his bashfully, her cheeks reddening. She ran her fingers through her hair. "You're so sweet," she said, her voice quiet. She rose onto her toes to kiss him, "I love you."

"I love you, too."

"And hey," she said, gesturing to her betrothal necklace, "I won't have to worry about turning down any awkward advances this time."

He frowned, "None of those guys are ever looking at your neck," he put in. She rolled her eyes and he added, "Remember the guy who made a pass at you while I was standing right next to you?" he reminded her.

She was grinning now, "He apologized!"

"Mm hmm," he replied, unimpressed.

Katara dragged her fingertips down the center of his chest and moved closer to him, "You have nothing to worry about. I have yet to find a better sparring partner than you. I plan to keep you around."

He scoffed, "I see how it is now." He laid his hand over his heart, "You're only marrying me because I'm the best punching bag you've found."

"You do look good when you're soaked," she agreed. She moved to kiss him again but he turned his face obstinately away, "You're good for other things, too!" she added.

"I am so insulted, Master Katara," he began, meeting her eyes again. He was struggling to hold back a smile, "and frankly I am shocked - shocked - that you would talk to one of your pupils this way."

She affected a sigh, "I can see I've offended your respect for the sanctity of the bending arts, Avatar Aang."

"Yes," he replied.

"I'm deeply ashamed," she whispered, "I'll go now."

She turned away from him as if she were about to leave the practice floor and he caught her around the waist, pulling her against himself with a chuckle. He bent to kiss her bare shoulder. She let out a little squeal as he nibbled his way up her neck, dissolving into laughter. He kissed her temple and then held her for a moment, his nose buried in her hair.

"I'm a little jealous," he admitted, his voice low.

She turned around in his arms to look up at him, frowning. "Don't you trust me?" she asked.

"What? Oh! No, no, not about that." He let his arms drop to his sides and swallowed, "I mean your relationship with Pakku."

A confused smile flickered across her face and she cocked an eyebrow, "I'm sure he'd yell at you about the inconsistencies in your water whip, too, if you wanted."

He waved her off, "You're my waterbending Master. I just think you're really lucky, you know?" He shrugged, "I know he's hard on you but it's because he cares." He ran his hand across his head and looked down, toward the floor, "I'd give anything to have Gyatso correcting my posture again."

Katara bit her lip, a sad sigh escaping her. She slid her arms around his waist and leaned into him, her eyes closed.

Katara knew the anxieties Aang had over being the last airbender. She could feel it in the way his energy was bound up in troublesome bottlenecks during healing sessions, the little knots of tension when she massaged his shoulders at night. He'd always been disciplined about his training, for as long as she'd known him. And despite his inclination toward playfulness, his focus on airbending was almost obsessive at times. He often spent entire sessions reviewing basic forms, the same motions over and over, as if he was worried he would forget them. He still had nightmares and often he could not articulate exactly what they were about. All she could do to reassure him was hold him, kiss his forehead, rub his sweaty back. She would whisper to him that everything was all right, the only time she ever lied to Aang, because she knew it wasn't.

Sometimes he wept, silently, trying to hide it from her in the darkness even though she could sense his tears.

They stood in the knee-deep water together and Katara ached at the hollow place she could practically feel inside him, her chest pressed to his. That void always made her feel helpless and small, though she never would have admitted it to him.

"He would be proud of you," she whispered. She felt him nod and his arms tightened around her.

His voice wobbled a little when he whispered back, "I hope so."