Summary: It was going to be another regular day working as a paramedic in the emergency room for Katara, until she stumbled upon a sick child. The italicized monologue at the beginning and ending of the story is elderly Katara talking to the audience, exactly like Jenny does in each episode. I tried to stay true to that format also by having major plot lines. But during the events, Katara is , exactly the same age as in their family photo. The events start in the morning, hence the first character is named Chen, which means morning in Chinese.
During her childhood, she was the only waterbender living in the South Pole and lived a peaceful life with her family. This happiness was shattered, however, when Katara lost her mother in a Fire Nation raid , Kya sacrificing herself to keep her daughter safe from harm. After her father left to battle against the Fire Nation in the Hundred Year War , she was raised by her paternal grandmother Kanna alongside her older brother Sokka. As a teenager, Katara and her brother discovered the young Air Nomad Avatar , Aang , who had been frozen in an iceberg with his bison , Appa , for one hundred years. She became Aang's waterbending instructor after their departure from the Northern Water Tribe, replacing Master Pakku ,  who had instructed them during their time there.
There are numerous Avatar: The Last Airbender fan theories. Most of them involve Aang, Katara, Zuko, and Toph, the most powerful benders in their respective elements. Sokka is often overlooked. Never fear, the boomerang wielding warrior from the Southern Water Tribe is getting his due.
Following the death of his mother and his father's leave for war , Sokka was raised by his grandmother Kanna along with his younger sister Katara. Hakoda left along with all of the other men in his tribe to fight the Fire Nation when Sokka was a young boy. Despite his desire to join his father, Sokka was not permitted to accompany the men on the mission and was left behind. He assumed responsibility for the tribe, haplessly training children to be future warriors, until his sister discovered an Air Nomad named Aang frozen in an iceberg.