|"Never show mercy."|
|— The Dai Li sergeant training Kai.|
The Dai Li sergeant was the Dai Li agent in charge of training the airbending conscripts to serve in the Earth Queen's army as part of the first airbending regiment. He was a firm instructor intent on training his pupils to be unyielding and fiercely loyal to their superiors.
Following Kai's capture, the Dai Li sergeant threw the young airbender into a prison cell underneath the Earth Queen's Temple and welcomed him to the army's first airbending regiment along with the other conscripts in the cell.
The Dai Li sergeant oversaw an airbending training session in an underground arena and reiterated that as conscripts, the airbenders were Earth Kingdom property and lived to serve the Earth Queen. He reprimanded Kai for showing mercy toward Yung and forced the former to attack with fervor and never to apologize. Sometime later, the Dai Li sergeant led a training session where he attacked the airbenders with earth disks to test their defensive skills. Frustrated by Kai's attempt to defend Yung, he attacked the young boy with a barrage of disks that sent him to the ground before telling him that he was not as good as he thought. He promptly evaded an airbending blast Kai conjured in anger and trapped the boy in an earth column, before ordering Dai Li agents to take the boy to solitary confinement.
That night, the Dai Li sergeant and two other Dai Li agents attempted to stop Kai from escaping with Bolin, Mako, and Jinora, stating that abandoning the Earth Queen's army was an act of treason punishable by death. During the fight that followed, he used a rock glove to grab Jinora, though this action prompted Kai to attack him with two strong gusts of wind, which tripped him up and slammed him down, rendering him unconscious.
The Dai Li sergeant is a harsh and temperamental man who thrived on his power as a superior. As an authority figure, he detested acts of disrespect toward his control and punished individuals who questioned him. The Dai Li sergeant is undyingly loyal to the Earth Queen's regime and carries out her orders without hesitance, to the point where he was willing to kill children for committing treason against the queen. He also harbors a somewhat cruel and sadistic sense of humor, showing amusement in his eyes when Kai told him he was not a soldier, replying, "You will be when I'm through with you."
The Dai Li sergeant was an earthbending master and used rock gloves in his operations as an officer. Although he fought alongside other agents, the Dai Li sergeant was capable of carrying his own during a battle. He was able to effectively subdue numerous airbenders in succession by precisely aiming for their chests and attacking them with earth disks, which he sent flying rapidly through the air using both his hands and feet. He was also very agile, successfully evading an airbending attack at close range with only a few seconds of reaction time.