Once upon a time there was a very rich but very stupid family who couldn't see what was right under their noses, which is really kind of funny because what happened to be under their noses was a blind but fantastically talented daughter who was just as good - probably better, actually - than any dumb son would have been.
Still, living in the world that they did - where women are weaker than men and the blind can't do anything for themselves - the family did the only thing they could: they pretended they had never had a child in the first place and secreted their poor, helpless daughter away from the big scary world at war. The girl understood that they were tying to protect her, but she still thought they were idiots.
They gave her earthbending lessons to keep her occupied during the very long days in which she was not allowed to go outside the walls of her home: big mistake on their part, but the girl would thank them for it eventually because it turned out that the better she got at earthbending the more she could see. In a few years she was better than her teacher.
Eventually, though it took her weeks to work out how to elude her parents, her nanny, her the servants, and the guards, the girl devised a way to sneak out of her home one nondescript night in early spring. You see, for a few years now, once a year, she would lay in bed and feel the earthbending going on somewhere near by. It was earthbending without a purpose - like building a wall or a dam - and that meant fighting. When she found the earthbenders - and the ring, and the screaming crowds - she was excited. When the fights were done and the champion declared, and they called for someone to challenge him, the girl climbed into the ring.
And at first, the champion refused the fight. The girl wasn't surprised: after all, she was blind and tiny. When she hit him with a really big rock, he changed his mind.
The fight was hard. She had never fought anyone before. She spent most of her time dodging and hiding, but when she finally did get a hit in she knocked him right out of the ring.
And when she went home that night she sat up in bed and cried because she had never been so happy in her life.
When she'd had to lie and say all her bruises had come from tripping in the garden, she wasn't allowed to go outside for weeks.
The years passed, and the girl continued to improve in her earthbending and dominate in the ring. Fighting wasn't a challenge any more: it was still great fun, but the thrill was gone.
Then one night, when they called for a member of the crowd to challenge the champion, an airbender stepped into the ring.
Now this is where the story really begins...