The Beyonder is the true god of the Blood On The Battlefield universe. It created The Overseer as a means to vent some of its infinitely increasing power, of which it took on a personality of its own.
The Beyonder has a disturbingly laid back nature, reminiscent of Killer Instinct's Cinder's demeanour. However, it still understands its role of being an omnipotent god and needing to intervene if there is severe discourse on Earth.
It chooses its latest body from those who have the ability to destroy a planet, taking their body and transferring his essence into them, of which they cannot reject once acknowledged. Once the process is complete, they cannot leave the outer space in fear of destroying the planet accidentally.
In Jess' case, even though she became a god herself, she still managed to harbour The Beyonder's power plus her own, counteracting her own to make her more stable.