Zahira's Wind (Avatar:The Last Airbender Fanfic)

Aang, first born son. Zahira, younger twin sister to Aang. Same bloodline, same air bending mastery, same destiny as Avatar. One night changes everything for these siblings as they are plunged into the icy waters of the North and South Pole. Zahira, who lived on the Northern Air Temple, flees when the Fire Nation manages to attack her home. Aang, who lives on the Southern Air Temple, flees when he hears of his destiny as Avatar. Now, as the twin Avatars awaken 100 years later, not knowing the other was alive, they must travel the world to master the elements in order to avenge the other. When an unlikely event manages to twine them together once more, Zahira finds that Aang has found his own family in the midst of his travels- along with his own enemies.