Jet was the teenage leader of a band of refugee children called Freedom Fighters. When Jet was eight years old, he witnessed his parents' deaths by Fire Nation soldiers. Jet grew up to become a sword-wielding vigilante, possessing a burning hatred for the Fire Nation and going to extreme lengths to enact his revenge, endangering innocent lives.
Jet disbanded the Freedom Fighters after an encounter with the Avatar; he and his friends LongShot and SmellerBee then decided to start a new, clean life in Ba Sing Se. When he tried to expose Zuko as part of the Fire Nation, the Dai Li rrested and brainwashed him into submission.
A second encounter with the Avatar's group reveals Jet to the truth of the Dai Li, and he helps them find Aang's lost Appa by leading them to Lake Laoquai, the Dai Li headquarters. There, Jet is fatally wounded and later killed by Long Feng when he overcomes the hypnosis placed upon him.