Water. ?
Fire. ?
Earth. ?
Air. ?
Long ago, the four nations lived together in harmony. Then everything changed when the fire nation attacked. Only the Avatar, master of all four elements, could stop them, but when the world needed her most, she vanished. A hundred years or so has passed, she appeared again as a water bender, when a man and a woman had found a little girl floating along on a platterhorse, when a huge block of ice had melted. Her name was Persephone and although her water bending skills are great, but she has a whole lot to learn before she's ready to save anyone. But I believe Persephone can save the world.
(My version of Avatar, more of a modern era. Hope everyone likes it.)