S1E15 · Book One: Water - Chapter Fifteen: Bato of the Water Tribe

Complete story — includes the ending

Sokka, Aang, and Katara find a seemingly-abandoned Water Tribe ship that belongs to their father's fleet. Camping out by the boat, Sokka and Katara are overjoyed when they are joined by Bato, an old friend of their father and fellow member of the Southern Water Tribe. Bato had been injured in battle and temporarily left behind by the rest of the Water Tribe soldiers while he heals. While they reminisce about the old days, Aang feels left out. A messenger arrives with a message from Katara and Sokka's father for Bato, with instructions to find him. Aang intercepts it and keeps it to himself, fearing Katara and Sokka will abandon him. He later comes clean about the message, but Sokka, furious at Aang for keeping it from them, is insistent on leaving to find his father, with Katara joining him. Meanwhile, Zuko hires a bounty hunter, June, to help him track down the Avatar, utilizing a large mammalian mount (shirshu) with a powerful sense of smell, using Katara's necklace as the scent. After Bato's comments on his loneliness after being left behind by his fellow soldiers reminds Sokka of his sorrow the day their father left, Sokka realizes that helping Aang is where he and Katara are needed the most. However, they're ambushed by Zuko and June who then use the message scroll to track down Aang. This leads to a fight, with Katara and Sokka helping to rescue Aang and resume their collective journey to the North Pole. Aang returns Katara's necklace to her after recovering it from Zuko during the fight.