So, first, pick some greek mythological characters and research their background. For example:
Eris: Goddess of discord, and hatred. Starts out small and weak, but grows until she touches the sky, and casts hatred down on all sides.... etc. (you'd have to do more research).
Posiedon: God of the sea. Zeus' brother... etc.
Long ago, there was a giant continent that connected North America to Europe, Africa, and Antarctica. The people of this land were very kind to all those around them. They were known as the Pacificans. They kept peace between the gods and the people, and prevented wars from starting. One of the Pacifican's greatest friends was Posiedon, god of the sea. He supplied them plenty of water, and they in return helped to keep the sea creatures safe from the items of people on land.
Eris, however, did not like this. It was almost impossible for people to hate one another with the Pacificans around. Wars were rare. Eris knew she needed to change this. So, to anger Posiedon, she blackened all the waters, and convinced the sea god that it had been the Pacificans. In his fury, Posiedon filled the land of the Pacificans with water, killing them all. This water became the Pacific Ocean, and war and hatred broke out everywhere.
