In the beginning, there were three entities. Chaos, who created chaos wherever he went, Order, who organized the chaos of Chaos into what now exists, and Balance who kept either of his brothers from becoming too powerful.
At the time of their death, each brother divided their power into three gems. From each gem, the first beings were born. Three primordals to protect the good. Three furies to punish the bad. Three fates to protect the balance.
Eventually, one primordial, Gaea, grew too proud to be ruled by the rule of three. She gave birth to twelve titans. For her arrogance, the Fates punished all primordals. They put them into a sleep to last to the end of time. Angered, the titans sought to awaken their mother and, in the process, lost one stone from each of the original brothers. With this event, the Fates made the decision to end their violent rule and gave Kronos three sons, and three daughters.
Some thousand years later, the Fates, who were less strict at the time, gave Gaea a second chance. They hoped that she could be redeemed so that the primordial gods could once again rule. But instead of righting her wrongs, the earth goddess created twelve more children to take the world by force. Angered, the fates aided the gods and heroes in their fight and returned Gaea to her slumber.
Now, many thousands of years later, the three brothers and three sisters' rule, and a new trio has been born. Not to rule the world, but to save it. Three cousins, sons of the reigning brothers, known by their people as heroes, feared and respected by their enemies, and who play parts they can't imagine in a prophecy kept secret since the beginning.