They came in short, drawn out raids. First they took the men. Next was the children. Her friends. Then the elderly, including her grandmother. They all disappeared, one after another. Her grandmother. Her father. Sokka. Her mother. And last, her. The raids had wiped out almost the entire tribe; Katara was one of the few survivors, along with women who had hidden during the attacks. Every time the snow turned black, and the sound of engines churned over the water, they ran. Every time, they took dozens. And every time, they came back, each interval shorter than the last.
Katara was the only one who still had hope. Maybe it was because she hadn't been captured yet; she hadn't experienced the dread of torture that was soon to fall upon her. She didn't know what was in store; she was just a child. A child with no clue of the horrors of the world. So when fate became reality, the young waterbender didn't understand. She was supposed to remain calm while foreigners were hauling her away to a criminal people's palace? She was supposed to obey the people who separated her from everyone she cared for, who killed hundreds of innocent people, who brought horror on the world? And she was supposed to work for the rulers of these disgusting people? No. No, she couldn't do it.
So Katara resisted. She refused to stand up, she refused to eat, to sleep, to speak... The other workers simply pretended she didn't exist. So did she. Her plan was immature; she didn't last long. Sure enough, survival came before pride, and she stood. She ate. She slept and talked and even worked, just so long as she could do something other than killing herself.
And she did so until she met Zuko.