Aang had a more prominent part in the promise, but is important nonetheless. He's the lead characters of the ATLA series. Personality wise, he's laid-back and calm most of the time but can get upset if someone is bothering his friends or offending his culture. I need a young sounding voice, a boy 10-13 sounding would be great. He has a high voice for his age. I understand some actresses can pull that off so feel free to audition ladies.  Some knowledge of the series might be helpful but follow this link for more - https://avatar.fandom.com/wiki/Aang