Thousands of years ago, God saw the state of earth and it's people, and was disgusted with the evil and corruption. And so, he left, and with him, he took all the mortal souls without sin.
They were barely a dozen.
After that, Hell and it's legions was free to unleash it's horror on the sinners. Eradicating humanity in seven days.
The only remnants left of humanity were the crystallized manifestation of their sins, Sanguinite. A gemstone that holds an unpredictable array of powers.
But even the evil of Hell itself couldn't be sustained in a vacuum. The brimstone realm of torment eventually evolved into a superpowered city. The demons within, formed their own cultures, politics, lifestyles, and even morals. they devolved from virtually immortal beings of chaos into simple people with temporary lives that aren't much different than humans. They rebranded the realm as "Helysia". A place once filled with pain and anguish, was now a place of luxurious lifestyles and opportunity.
On the surface, True chaos still reigned. the demons that dwelled there mutated into all manners of twisted creatures. All of them are caught in an endless gang war for territory and resources.