A/N: Hello everyone! I'm still somewhat new to writing for the Atla fandom, but I've been doing my best! I started this fic months ago, intending it to be a oneshot, but I'm so excited to share some of my worldbuilding and culturebuilding that I'm breaking it up into chapters. XD

It's almost done, too!! So expect updates at least once a month (I'll try to spread them out like that so it'll hopefully be finished by the time I catch up to where I'm writing now.)

That being said, I first found the whistle-speak headcanon from the story 'I'm Here' by MadameFluffnStuff on Ao3 (https://archiveofourown.org/works/26411236), and it's solidly become part of my own headcanons for this world. I've got several OCs that'll appear in this story, as most of what I'm writing here takes place before the Genocide of the Air Nomads.

Anyhow, please enjoy! This story will contain some darker themes, so please be wary.

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Aang's eyes snapped open to stare at the high-vaulted stone ceiling. He was sore and hurt everywhere. His lightning scar throbbed in time with his heartbeat and he felt like he'd wrestled a flying bison during rutting season and lost. His brows furrowed as he tried to remember what happened. He'd been in the middle of fighting Ozai when a Lion Turtle had shown him another way. And he'd tried it but...

He bolted upright, hand clenching his chest when his scar flared painfully-something he'd started to grow used to over the last few months. Had they lost? Where were the others?! He heard someone shift in a bed nearby and whipped his head around, only to freeze. He knew this room. He knew those children laying in their beds, heads shaved and clothed in yellow and orange. It was a sight that had haunted him for nearly a year. Something he knew he'd never see again.

His heart pounded in his throat as he silently airbended himself to his feet, only relaxing minutely when he had his staff in his hand-the familiar wood an old comfort he'd thought lost forever. He leaned somewhat heavily on his staff, still utterly exhausted from his battle with Ozai, and silently left the room.

Slowly, as if in a dream, he made his way down the familiar hallways and outside. There were... people. Monks on late night strolls, bison sleepily floating across the sky, lemurs gliding gracefully from one tree to the next. Aang couldn't help but stare as one of the nocturnal monks casually flicked his staff open and glided to another platform. He couldn't remember the last time he'd seen someone else airbend.

It felt strangely foreign. His ears picked up the faint sound of whistling, and his eyes prickled with tears. Whistle-speak was a universal Airbender language. Some called it the official tongue of the Air Nomads, and it was created by braiding strands of wind together to create specific tones and rhythms. Foreigners said it sounded like beautiful flute-like music.

To Aang, it was the first time he'd heard his native tongue in what actually felt like a century. He almost braided his own tune, his own not-words, but he was terrified. It was nearly impossible to lie in the voice of the wind. Emotions drenched whatever you said to the breeze, and it could carry for miles from the lips of an Airbender.

He was afraid that if he whistle-spoke now, he'd worry someone. He resolutely ignored the memories of desperately whistle-speaking as he traveled with his friends, praying to any Spirit that might listen that he'd get a response one day.

His friends.

Aang sat numbly on a sunning rock overlooking the grandness of the Southern Air Temple. If this was real, and he was actually in the past... Then what happened to his friends? Katara and Sokka and Toph and Zuko and Suki and everyone else he'd met on his journey.

Abruptly, a sickening mixture of grief, relief and guilt hit him like a tsunami. He stifled a sob as best he could, forcing down the familiar sensation of the Avatar State attempting to aid him with whatever had him so grieved.

They were gone. Not even dead, they just... no longer existed. In a way, Aang thought that was worse. It was just like when he'd awoken after being frozen in ice for a hundred years. Back then, he was the only person who remembered the Air Nomads. Their ways and traditions and customs. It was solely up to him to keep his people and culture alive.

Now he felt quite similarly. He was the only one who remembered his second family. Who could keep them alive despite the fact that they'd yet to have been born. He realized belatedly that no matter which era he lived in, he would not be able to feel completely satisfied or happy. That he'd either grieve the loss of his people, or the loss of his family. He could not have both.

For a moment, he rested his foot against his knee, fingers lightly tracing the scar from Azula's lightning. The familiar rough texture was somewhat grounding, despite the fact that the pouding in his scar had since moved to the pounding in his head. It meant that it'd been real. That Katara had healed him, which meant she'd been alive at one point.

A familiar chittering sound had him glancing to his left, where a flying lemur tilted its head in concern. It patted his leg softly, chittering more urgently, as if desperate to somehow comfort him. Aang eyed the patch of grey that tipped the lemur's left ear-something he'd stared at a million times.

"It can't be..." He stared at the lemur. "Momo?"

The lemur clapped his hands, swinging himself up on Aang's shoulder and curling his tail around his neck in a familiar gesture and made a soft purring sound as he nuzzled Aang's arrow-something Momo did whenever he noticed Aang needed the comfort.

"It is you!" His lips curved into a wide grin, and something hopeful sparked to life in his chest. If Momo was somehow here, then maybe Appa remembered as well. Maybe he wouldn't be completely alone.

At the start of his journey, Aang had stood beside Momo and Appa and declared that the three of them were the last of this place. The only ones that could carry on the legacy of the Air. Now he felt like he and Momo-and hopefully Appa-were the only ones of a future-that-may-never-be. And that it was up to them to keep their friends in their minds and hearts to ensure their existence was real.

He found his gaze drifting skyward. The stars were familiar-one of the only things that hadn't changed in the century that he'd been away for. He could almost hear Sokka pointing out some of the southern constellations and explaining what they meant for the hunting season. How the Hunter constellation always pointed his spear in the direction of home, and the Tigerseal constellation liked to swim towards promising fishing grounds in the spring.

"I miss them." He whispered to Momo, who made a rather sad whine.