The four elements.

According to legend, there always was fire, air, earth, and water, but they floated along on separate plains, unable to be connected. Until one day, they all connected in the same place at the same time. The fire burned the earth to give it shape, water flowed over it, putting out the fire and air came on top, sealing the three together. But there was a problem. Having been cut off with water, the fire needed somewhere where it could be safe. So it rooted itself in a human, giving it life. Sia was reckless, destroying everything until finally water came in to put out the flames. Once inside, there was unity between the two. But soon the world was being flooded and flamed. So earth came in to blood the flood, and air came in to sooth the fire.