Yahoul is one of two primary antagonists in the pilot episode, and serves as a yin and yang with his partner, Griffin. Yahoul hails from a warrior planet where combat and battle were their way of life. Honing his skills of battle and prowess in the hunt, Yahoul's planet was then later devoured by The Hive. The lone survivor of his species, Yahoul fled. Finding the planet Earth, Yahoul sought refuge amongst ancient humans. 

Settling in ancient Egypt, Yahoul's power to shapeshift his form to match native creatures (and use a variety of abilities depending on the form he took),Yahoul became known as the ancient Egyptian gods humans would come to worship, and shaped early humans into warriors and conquerors.

In modern day, none truly worship his teachings anymore, and he has fallen into the silent protector of Earth from invading malicious aliens (Like Rookie and Senior), and will let nothing stand in between him and his goals, even if sacrifices must be made for the greater good of the planet.