Sokka is the older brother of Katara, he along with his brother who finds Avatar Aang while still immersed in the ice at the South Pole along with his flying bison named Appa to then take Aang to the southern water tribe settlements and eventually gone away wandering accompany Avatar Aang seek identity as Avatar ruler of the four elements of nature.
While wandering along Aang, they met a blind girl named Toph Bei Fong, though blind but he is very good at controlling soil science, far exceeding even the ability to coach suggested by his parents and eventually they go up and down with.