The Lunar Warrior [ATLA FF]

As the eldest son of the chieftain he was tasked with protecting the village when his father left to aid in the war. As an older brother, he has to take care of his younger siblings Sokka and Katara. After their mother was killed, too much changed. He didn't have time for fun and games with war on their borders. To keep his remaining family safe he had to close off his heart and train relentlessly for the battle he knew they'd face eventually. The Avatar wasn't coming back. Or at least, that's what Ayaan thought, until a bald kid with blue arrows showed up.