Kai

Kai is an orphan who suddenly became an airbender after the Harmonic Convergence of 171 AG. He is a mischievous thief who was later caught by the Dai Li in Ba Sing Se for using airbending.

History
Kai grew up an orphan. When he was finally adopted by a nice family six months after the death of his parents, he took advantage of their kindness by stealing their life savings and spent six months on the run from Earth Kingdom authorities. Following Harmonic Convergence, he soon discovered he possessed airbending. A few weeks after, he encountered Team Avatar, who was searching for airbenders to rebuild the Air Nation. He told them a false story of how his parents were killed by outlaws who were pursuing them, earning their sympathy and quickly being accepted in their company. Just as he boarded their airship, ready to depart, however, a sheriff and his deputies arrived, whom he falsely claimed to be outlaws. After Avatar Korra bested them, the sheriff revealed Kai's true identity as a thief. The boy attempted to run off with his loot, but was caught by Mako. The sheriff quickly took custody of the young lad, intending to send him to prison. However, in exchange for returning the life savings to Kai's family, Korra convinced the sheriff to allow Kai to turn over a new leaf with Team Avatar. Though the compromise was accepted, Mako warned Kai that he would be watching him.

Upon arriving in Ba Sing Se, Kai's kleptomania got the better of him, and he slipped away to use his airbending to pickpocket the wealthy. When Mako and Bolin discovered his disappearance and return to his thieving ways, they chased after him. Kai managed to give them the slip as he left them on a train while stealing their wallets so they could not pay for the fare back to continue the chase. He later settled down in a luxury resort under the alias Fong. However, the next night, after successfully conning another citizen, Kai was captured by the Dai Li and thrown in prison with other airbenders with the intention of conscripting them into the Earth Queen's army as its 1st Airbending Regiment.