Sokka was leading an expedition to the South Pole. It was five years after the War had ended. Katara married Zuko in a diplomatic marriage at the war's end, but came to love her husband. She came often to the South Pole, so it was fine. Aang wandered around for years but eventually settled down with a nice Earth-bending girl. They now lived in the Eastern Air Temple when Aang wasn't helping the rest of the world. Sokka took over the Water Tribe after Hakoda died. He hadn't married yet, but knew that he would have to eventually. In the meantime he was happy.
They got to the Water Tribe the next morning. People waved when they pulled into the docks. The new Chief, Sadamo came running down to the docks. "Sokka! Pleasure to see you again! How are things in the sister tribe?" Sokka clasped his friend's hand warmly. "Fine. Katara's expecting her second child, the seals have come back, and the tribe has remained healthy this year. You?"
"Oh fine, all fine. We have some warrior trainees and Water benders dueling in the main courtyard tomorrow morning I'm sure you'd be interested." Sokka's eyes lit up. "You have Warrior Training here?"
"Why yes, we want our walls to be protected." Chattering and laughing the friend's went to his house to eat. They spent the night telling each other all of their tribe's latest news.
The next morning Sokka woke before the dawn. He lay still for a second, then dressed and left his room. He jogged up to the walls and climbed up to the guard post. "Hi, I'm going for a quick jog. Just wanted to tell you so I didn't get shot." The guard looked at him. "You might want to run that way. If you go the other way you'll have to contend with Karuko for running space."
"Who's Karuko?"
"She's one of the warriors. She's only a trainee, but very fast and very smart." With that in mind Sokka took off. He ran lightly leaving almost no tracks in the snow. He had worked very hard at this, because it hid the most scent and track. He saw a figure running almost a half-mile ahead of him. Whoever it was really good, because they were barely leaving a track every hundred yards or so. It must be that Karuko person the guard mentioned. She maintained a steady pace all the way and left by the staircase. Sokka finished his run just as the sun came up. He ran back to the palace and changed clothes for the training session.