Kya was born near the end of 111 AG in the South Pole. She discovered her waterbending skills at age four while playing in the snow with her parents. After this, her parents, primarily her mother, began instructing her in waterbending. Under their tutelage, Kya honed her waterbending skills from a young age, and soon became a waterbending master by the time she was fifteen.
During a trip to Kyoshi Island when she was twelve, Kya met and befriended fifteen-year-old Talia, the daughter of Ty Lee. The two girls got to know each other very well, and, much like their mothers, began a close friendship.
In 127 AG, when she was sixteen, Kya moved with her family to Republic City in the light of rising crime. In July of that year, she was on a walk with her youngest brother, Tenzin, when the two were ambushed by members of the Red Monsoon Triad. The siblings were bloodbent and captured, being held for the remainder of the night. However, they were busted out after the Metalbending Police Force discovered the Red Monsoon's holding cell, an operation led by their family friend, Chief Toph Beifong. After the victory, Toph and another officer brought Kya and Tenzin home to their parents. It was in the light of this that Katara was forced to teach Kya bloodbending in the event that such a situation happened again.