Sargon is the Demon Chief of the Demons. He is over a trillion years old and one of the oldest beings in existence. He seized power twice. Once before the Diamondae and then again after the Diamondae were obliterated.
Existing under the comparatively tame slavery of the Diamondae allowed him to gain insight in how to be in control and how to rule effectively. He feels jealous of Tyra Kolaq'blegae's slavery and is annoyed by their disregard for death. Although he is older than any Empirian, he is infuriated by their lack of care of piety and devotion to the concept of an end.
Sargon was the one that decided to take control over Kharat distribution from the Grim Reaper. The lack of efficiency displayed bothered him greatly and the bureaucratic Demons agreed that something ought to be done, so they took it over, breaking barriers in the process.