*OK, there seems to be a little confusion over this: the girl Nora in this story is Zuko's daughter, as a shortened version of Honora (the fandom's designated nickname for the character). I just thought using Honora would be too silly, so I shrunk it a bit so it sounds more like a real-ish Fire Nation name.*
"Bumi, can I go-"
"Shush!" Bumi quickly focused his attention back to his task: forming more snowballs from the snowy ledge that acted as their "cover."
"Why are you shushing me for? Kya's ten feet away; she can't hear us!" Tenzin felt his patience running low.
"Don't let your guard down, Zin. Our foes are not to be taken lightly." Bumi warned him as he patted the last snowball to perfection. He peeked over the ledge to look at Kya, down by a frozen pond where she was giving Lin and Nora skating lessons. Nora seemed pretty adept at it, unlike Lin who had slipped more times than he could count but refused the girls' help every time.
"I'm going home." Just as Tenzin was about to get up, Bumi pulled his arm down so hard his face almost landed on the snow.
"No! I need you for my strategy to work! With this ledge, we've got the higher ground. They can't see us, and with your airbending, they can't predict where they're getting pelted from." Bumi whispered excitedly with a manic grin as he recounted his plan. Tenzin acknowledged that this was his brother's natural state… and that never stopped worrying him. "My plan's brilliant!"
"It's dumb," Tenzin stated bluntly.
"I stand by 'brilliant,' But enough flattery, let's get ready to-!" Bumi looked down, but there was no sign of the girls. His grin started to pull down to a disconcerted frown.
"Looking for me, boys?" The boys turned, and saw the fierce smugness in their sister's eyes. It was then a revelation struck Tenzin: At age four, he was smart enough to mind Bumi. Until age eight, he'd been dumb enough to ignore Kya.
—-
Lin and Nora went ahead of the siblings to Avatar Aang's manor. They found the adults in a pagoda out in the front yard, chatting and drinking tea while gathered around a built-in hearth. The girls shook off their snow-coated boots and skates before joining their parents around the pagoda fireplace.
"So how were skating lessons, Lin?" Her mother was the only one lying down, resting her head on one hand like she owned the place as she slurped her tea. As Lin held back on her answer, she sensed a low rumbling. The others soon turned around as the sound grew louder, and Lin could never forget the next thing she saw.
Tenzin was on an air scooter, had Bumi holding onto him for dear life, and both of them were chased by a giant rolling ball of snow… at the top of which was Kya, standing tall and laughing her head off. That snapshot of a moment buried its place in its audience's mind forever, even as the three quickly rushed away from sight. Everyone paused in awe of the sight, except her mother, who probably shrugged it off as Appa running around with the kids again, and Nora, who took the chance to just pour herself some more tea.
"It was fun," Lin answered with a smile.