Sokka felt obligated to protect his younger sister as urged by his father before his departure to the Earth Kingdom.
Sokka took this task very seriously and became somewhat overprotective at times.
When Aang flew off, Team Avatar separated from the Water Tribe warriors again Sokka strove to be like his father and shared many personality traits with Hakoda; such as brilliant planning, leadership, bravery, inventive ingenuity, and sense of humor.
Bato remarked upon this, saying, "You're definitely your father's son", after Sokka laughed at Hakoda's attempt at wit in naming his bomb the "stink and sink", albeit in an unamused tone.
She took on such an important role in Sokka's life to the extent where whenever he tried to picture what his mother had looked like, Katara's was the only face that came to mind.
However, because of the history they shared and the struggles they had to overcome as children when their mother died and their father went off to fight in the Hundred Year War, the two identified with each other and were very close. When her hands were accidentally burned by Aang, he yelled at him and knocked him down,"I never told anyone this before, but honestly, I'm not sure I can remember what my mother looked like.
He proved to be very loyal to her; when Katara decided to defend the fishing village of Jang Hui against the Fire Nation Army, he put his anger aside in order to help her.
When she believed Aang's actions to have endangered the village, she took Sokka's side in the argument.However, she came to see that it was her grandchildren's destiny to journey with the Avatar and saw them off, telling her grandson to take care of his sister and not to tease her.Sokka and Katara had a typical sibling rivalry, and despite constant bickering in the course of their travels, the siblings loved each other dearly.Sokka reunited with his father at Chameleon Bay, where Hakoda recognized his son as a man.Sadly, the reunion was cut short when Aang came with news of Katara's capture in Ba Sing Se.