A/N: Let's call this a missing scene of sorts for "Promises to Keep" by Kimberly T. Read that first, otherwise it won't make much sense.
For those who have read it some time ago, here a brief recap of the relevant part:
After a, at times turbulent but all in all very civilized, stay as a prisoner on honorable parole on Zuko's ship, Katara is finally reunited with Aang and Sokka – and has now a really hard time convincing her brother that nothing heinous has been done to her, culminating in the following exchange (Chapter 10):
"Come on, Katara; this is the Fire Nation we're talking about! The same people who raided our home and killed our mother; they're all evil to the core!" He swallowed hard and took a deep breath, seeming to steel himself before asking, "Did they… dishonor you?"
Katara just stared at him, wide-eyed and blushing deep red, while Aang scratched his head in confusion. "Did they what? You mean, did they insult her or something?"
Katara spoke slowly and clearly, as her eyes drilled holes in Sokka's skull: "No, Sokka, they did not dishonor me. And I'm going to leave it to you to explain to Aang what that means… later."
I commented on the quoted scene, Kimberly challenged me to write the explanation. And this is what became of it (perfectly T-proof, I swear):
Later turned out to be so much later, that Sokka had started to hope, the easily distracted Air Nomad might have forgotten about the incident already, but early the next morning, while they were packing up camp, Aang suddenly perked up and asked, guilelessly, "Oh, Sokka, I just remembered, you still haven't explained what you meant with dishonored."
Gah! The young hunter threw a beseeching look at his sister, but Katara simple glared back, eyes firm and cold as old ice. The sort of ice you could build a village on, because it would neither melt nor crack for the next few hundred years.
Nothing to it, then. But how to even start explaining that to a twelve-year-old? A twelve years old monk with a hundred years' worth of naivety, to boot? Sokka had known the basics of procreation at twelve, naturally, but it hadn't been until shortly before the warriors had left the village, that Bato had told him about… some of the more sordid details. And even then he had not truly realized the implications until Gran-Gran had pulled him aside, right before their departure, and had spelled out, in graphic detail, just what he was expected to protect his little sister from. It had taken the angry jerkbender to get those images out of his head again.
He nervously cleared his throat. "Uh, err, say Aang, do you know where the little babies come from …?"
The expression on Aang's face was equal parts exasperation and confusion. "Of course, I know! I may be young but not that young! But what has the Solstice festival to do with anything?"
Whew, that cleared that hurdle! Sokka thought in relief, before the second sentence caught up with him. "The Solstice festival?"
Utterly baffled, the Water Tribe boy shared a look with his sister, expecting to see the same sort of mystification on her face, but instead Katara suddenly looked as if she might sick up any moment.
"Katara..?" he called out worriedly, but the younger girl just shook herself together, grabbed a half-filled water-skin and hurried towards the nearby creek.
"You guys clear this up among yourself," she called over her shoulder, just before she vanished in the undergrowth.
For a moment Sokka considered hurrying after her, but an upset waterbender near a body of water wasn't someone a smart man disobeyed without a very good reason.
"Riiight. Girls, I'll never understand them," he muttered under his breath, before turning back to the other conundrum on his hands.
"Aang, what has the Solstice festival to do with babies?"
The young Avatar, who had stared, half worried, half perplexed after Katara, gave a start, and then a wide, mischievous grin.
"Are you sure, you know where the little babies come from? At the Solstice festivals, the younger monks – between fourteen and fifty, I mean, not the kids, eeewww – go to the Eastern and Western Temples, and meet the nuns there."
The tattooed boy frowned slightly. "Gyatsu said, you don't have to go there, and it's the same with the nuns, of course, and even if the nuns like to, they still say no, sometimes, because it would be disharmonious progeny, the head nuns keep records of those things, I think…"
"Whoa, whoa, wait a minute! You trying to tell me that… that Air Nomads only do it twice a year?" Sokka couldn't help it, he started sniggering. Aang gave him a look of wide-eyed confusion and the older boy lost it completely.
"Sorry, sorry," he said, when he'd caught his breath back, "I know it's not a laughing matter." Indeed not! The reason why he had started this awkward discussion in the first place caught up with him and sobered him abruptly.
"Look, Aang, no matter what the monks told you, people aren't caribou-bears, they don't have a fixed mating season. People can make babies all the year round."
"And," the young hunter swallowed heavily, "they can do the thing without caring about babies, at all."
The puzzlement hadn't left Aang's feature in the slightest. "But if you don't want to seed... why would you do it?" he asked with a frown.
Why? Why? And Seed? La's big fat claspers, Air Nomads really go about these things differently than other people, huh? Had to be that lack of meat in their diets, Sokka decided after a moment's consideration; temperance in all things was all good and well for a monk, but only twice a year – that just wasn't natural. He was about to start a list of arguments, to try once again to convince Aang to eat meat, so the kid would be properly ready for puberty when it hit, before an inner voice, that sounded scarily like his younger sister, sternly told him to Quit stalling!
The Watertribe boy cleared his throat, again. "Weeell, one of the words for it is making love. When two people really, really, really love each other, it's great fun to do.
Apparently," he added, for honesty's sake, but since he'd rushed through the words with a speed worthy of an exited airbender, Aang hopefully wouldn't notice.
"On the other hand, if there isn't any love, it's one of the cruelest things you can do, to… to take another person by force!" And please, please, please, don't let me have to get any more graphic than this! He really didn't want to dig up any of Gran-Gran's warnings.
"But…, but…" the young Avatar went stock-still – which was downright unnatural for the usually so energetic boy.
"That's dishonorable. That's what dishonor means, isn't it?"
Not… exactly. But close enough for today. Sokka nodded mutely.
"I… I… I have to go!" A swoosh of displaced air and instead of the younger boy there was only a dust devil, ruffling anything as yet unwrapped.
Deeply discomfited, Sokka went on packing.