Inspired by HeadCannons Volume 2 ( .com). Disclaimer: I am not the Avatar or the producers of Avatar, heck I'm not even the Cabbage Merchant.
For the first time in nearly two centuries, the dining room of the Northern Air Temple wasn't empty. Surrounding the long, rectangular table were airbenders laughing and jokingly blowing gusts of air at each other when Tenzin wasn't looking. But not all were present.
"Where's Kai?" Peema asked her husband.
"Kai?" Tenzin looked down the table and saw the seat next to Meelo empty. Jinora noticed her father's questioning gaze.
"I think he's still in his room."
"Really? That's odd. Kai is never late for dinner."
"Well, he has been acting rather strange lately. I hope he's alright." Tenzin stood.
"I'll go check up on him."
Only after persistently trying to convince Tenzin that—despite a lack of worldly possessions—they at least deserved some privacy (not to mention a night of decent sleep, free from Bumi's snoring), did he allow the airbenders their own rooms in the upper levels of the temple. Kai had taken the first room on the right in a hallway on one of the lower levels, relatively close to the dining room and kitchen (not coincidentally). The airbending master knocked.
"Kai, why haven't you come to dinner yet?" There was no reply. Tenzin reached for the doorknob. "Is everything alright?" Suddenly, Kai burst through the door in a gust of wind and slammed the door behind him.
"Of course! I'm fine, what's for dinner?" Kai said while quickly increasing the distance between him and his room. A hand grabbed the top of his head, freezing him in his place.
"What are you up to?"
"What do you mean?"
"Don't play innocent with me. You've been acting odd lately."
Kai placed a hand over his heart in dismay. "When have I ever—" From his room, a loud snore interrupted him mid-sentence. Tenzin went to open the door, even as Kai tugged his arm—insisting that the noise came from his hungry stomach.
In the room, a baby bison lay on Kai's bed, sleeping soundly and snoring loudly every so often.
"How could you take this baby away from his herd?"
"But I didn't! I found him alone in a small cave by the side of the mountain. His siblings weren't there and his paw was injured. I went every day to take care of him and his parents never came." Tenzin glanced back at the bison and noticed a bulky bandage wrapped around his forepaw. He gave an exasperated sigh, but when he spoke his tone was gentle.
"That still doesn't mean he can stay here. He's from a wild herd and another wild herd will adopt him, but not if he's cooped up in here."
"I know," Kai sighed, eyes suddenly very focused on the floor.
"But perhaps it is time for you to choose your own bison."
"Really?" The boy's face lit up in anticipation.
"Well, I suppose that's up to you and the bison. I will tell you a saying of one of the nomads that you won't find in any readings, but that I know because my father told me: 'Choose well. A sky bison is a companion for life'."
"Don't worry, I definitely will."
"Well, if you're so enthusiastic, we'll head out at dawn tomorrow."