A good place to start would be the beginning. Yet how far back must one go to reach the beginning? In this instance, hundreds of years. You must understand the events from the past to understand how they would shape the future into that which we know it.
Marriage for politics, that's how it all started. His sire and dam were mated, to secure political alliances. There was no love for one another, they did their duty and produced an heir. Once the alliance was cemented with the creation of the heir, his dam returned to her palace in the sky and his sire continued to roam, building his armies and conquering.