When Zuko was traveling through the Earth Kingdom on his own, he came across the plains village, where he covered for Lee, Gansu's son, who had thrown an egg at one of Gow's men. The boy, owing Zuko, invited him back to the family farm where Zuko met Gansu. Gansu immediately welcomed Zuko after learning that he had stood up against Gow and his men. Gansu and Zuko proceeded to work on the barn, fixing the roof together. He later told his son to stop pestering Zuko with questions that revolved around the latter and his background, stating that a man's past was no one else's business.
When Zuko was about to depart from the pig farm to continue his journey, Gow, the leader of a corrupt group of Earth Kingdom soldiers, approached the farm and informed Gansu that his older son's battalion had been captured by the Fire Nation. When his men proceeded to mock that the Fire Nation would dress up the entire battalion in Fire Nation uniforms and put them on the front line unarmed to serve as fodder, Gansu told them to watch it. Gow threateningly approached Gansu, but was cut off by Zuko. After the corrupt soldiers took their leave, Gansu announced that he was going to go to the front to find Sensu and bring him back.
Gansu was a respectable farmer and an honorable person. He was intolerant of people who abused their power and, much like his young son, stood up for himself against such people, even though it sometimes got him into trouble. Gansu cared deeply for his family and loved his sons; when presented with the possibility that his oldest son might be dead, he was willing to ride into the heart of battle in order to find him.