Gravital (All Tomorrows)

The Gravital were a robotic posthuman species that evolved from the Ruin Haunters.

Origin
Due to their knowledge about the Star People and the Qu, the Ruin Haunters were able to develop a civilization while other posthumans were still non-sapient animals. This gave them an edge that matched that of the Asteromorphs, but also led to them seeing themselves as the sole heirs of the Star People.

When the sun of their planet started to rapidly expand, there was nothing they could do to stop this. To save themselves, they built spherical, robotic bodies that floated and manipulated their environment through gravital manipulations. At first, those spheres still contained the brains of the ruin haunters, but later they were fully mechanical, becoming the Gravital.

But still, they retained their human dreams, human ambitions and human delusions of grandeur. Their artificial bodies made space travel easy for them and they started colonizing other planets.

Galactic Conquest
When the other posthumans, started by the Killer Folk and the Satyriacs, joined together into the Second Galactic Empire, the Gravital refused to communicate with them and stayed for themselves.

After long preparations, including developing better bodies capable of interstellar travel, the Gravital began to wipe out their posthuman cousins and all other organic life within about 10,000 years. They managed this through blocking their suns with million mile wide sails and, if that wasn't enough, finishing the worlds off via orbital bombardment.

They did all of this without fully realizing the life of the other posthumans, having spent so much time without biological bodies that they were no longer capable of recognizing biological life as what it is. So what was genocide to the other races was more akin to tearing down an abandoned building to the Gravitals.

The only biological species that survived the invasion were the Bug Facers, for reasons still not completely understood. They were one of the first to be attacked by the Gravitals, but they were left alive and redeveloped through genetical engineering into the Subjects.

Civil War
There were some fractions in the Gravital empire which developed, through science, philosophy and religion, an understanding of universality of life and the common origin of organic and mechanical humanities. Initially, they lived in seclusion and created subjects that were allowed to do as the please, and eventually the movement gained enough momentum that it could be practiced openly without being punished. Some Gravitals even fell in love with their subjects.

The seething intolerance between the two factions finally broke when some Tolerant Machines wanted so set several worlds aside for the unrestricted development of biological life. All hell broke loose and the Machine Empire; the apparently seamless monolith of the galaxy, experienced its first short, bitter civil war.

Downfall
Over a long time, the Gravital and the Asteromorphs nervously eyed each other. The mostly kept for themselves, as the Asteromorphs inhabited the void while the Gravitals occupied the planets, but in almost every inhabitable system, the two Empires lived side by side and there was a strange tension between them, due to both sides knowing that they could destroy each other and whole planets and solar systems.

But in order to resolve the internal tensions created by the civil war, the Gravital Empire needed a common enemy to unite against, and the Asteromorphs were chosen as this enemy. The war spanned many million years and life (both biological and mechanical) was lost in numbers that let the Gravital's genocide look trivial. But in the end, despite huge losses, the Asteromorphs succeded in nearly completely annihilating the Gravital.

After that, the Asteromorphs used the surviving Subjects to repopulate the planets and become true creator-gods for the worlds populated by their descendants. But they didn't completely destroy the Gravital, some of them being remade into the New Machines and living as second class citizens in the new empire.