Sometimes Aang forgot how old he was.
With a flick of his long, muscled arms he'd send his shrieking daughter into his arms, letting her clamber onto his back and ride the air scooter with him. They'd race across Air Temple Island with the wind and the sea breeze blowing in their faces.
Aang would bend with her, splashing her from inside of his octopus and teaching her how to do the same. He'd wrap her up in a watery tentacle and pull her towards him, turning their childish sparring match into a tickle fight.
Then he realized that he was an adult now.
It was never, ever of his own accord. Avatar or not, he saw no harm in smiling or laughing with his children. On his own, he'd never realize he wasn't supposed to make his family crowns out of flowers and play fairies with them.
The first realization that this may not be quite correct was during a meeting with a Northern Water Tribe ambassador. They'd had him to visit Air Temple Island, and they'd been discussing trade agreements when Kya ran in.
"Daddy!" she sobbed, holding out her arms. "I'm hurt!"
Aang could she that she was; her chubby elbows were welling with blood. He immediately ran to her, falling onto the ground and wrapping her in his arms.
Kya buried her head into his shoulder, and her tears formed a large wet spot on his formal robes. He made a mental note to order new ones; these would probably be ruined.
"I w-w-was working on a new bending move to show Mommy for when she came home from visiting Grandpa, and I f-f-fell into the fountain, and I was so scared, Daddy!"
"Oh, Kya," Aang said, wiping away her tears, his voice soothing. He removed his arms from around her and placed them on her elbows. They were already damp, and so it didn't take long for the familiar blue glow to appear. His eyes flashed white.
He didn't know how to heal, but Avatar Kuruk did.
"That sounds like a real warrior's battle," he told her, his voice serious.
"R-really?" she asked, her eyes wide. Her parents were the best fighters in the world to her, and they never lied. Having them say she was a warrior was a big achievement.
"Definitely," her father replied, "I don't know if I've faced a situation more dangerous, personally."
"What about when you got your scar?" Kya was starting to feel better now. There was very little more comforting to her than wrapping her arms around her father's neck and grieving her sorrows. He sat in his meditation position, legs crossed so that she could perch comfortably in his lap. His arms held her tightly to his chest.
"That doesn't count," he explained, "I had your mom to heal me. You were brave all by yourself."
Kya was sitting up straighter now, clearly proud.
"Do you want to play Kyoshi Warriors with Aunt Suki and Uncle Sokka and me?" she asked, wiping away her tears. Aang grinned. Sokka and his wife told his daughter too many stories.
"I'm sorry, honey, but I have to talk to this nice man right now. Why don't you go back to them? They were nice enough to come watch you, and they're probably really lonely right now. When I'm done I'll help you practice your waterbending for mommy."
"Okay daddy. I love you."
"I love you too, you crazy Kyoshi Warrior. Go get them!" Kya ran off, wounds forgotten.
Aang looked up to the man he'd brought over, apologies on his lips, but the judgmental look on his face was hard to misread.
The Avatar blushed, suddenly embarrassed of his mistake. He'd never hear the end of this, not from the Northern Water Tribe or anyone it associated with, and definitely not from Kyoshi the next time he saw her.
Still, years later when Bumi and Tenzin came to him with their bruised elbows or pride, he always did the same.
Aang never learned.