Pan Post 137 takes place in an alternate reality where the Greys of Mirare were the favoured people instead of the humans of Earth. In this alternate NeSiverse, the Greys came to dominate their reality and used a combination of both magic and technology to rule the other species, taking many as slaves. After the Time Lock War, devastation struck the East pole of Mirare and the magic of this reality is weakened. The God-Emperor of Greykind determines that they shall invade the alternate universe where humans are the chosen people and claim its ultranexus to fuel their magics. They redub their empire the Greyarchy as they do not wish to be confused with The Imperium.
Billions of years ago, Mega Jonestown Prime ruled the NeSiverse (though its hand was light, as its gods were wrapped up in their own agendas), and they initiated a grand contest - who would create the greatest wonder, for the God-Monarchs to bestow their blessing and favor upon, to center their entire cosmos around?
Gods and high muckity-mucks across the NeSiverse (and reportedly, some from outside it as well) created incredible things - but the God-Monarchs chose the shared entry created by three gods (the Runekeeper, Aeon, and the Three Fates): humanity, and Earth.
But for anyone who knows the nature of the multiverse, it is known that there are an infinite variety of possible worlds, alternate timelines where every possibility exists. And so, in one alternate timeline, the God-Monarchs instead chose the Greys of Mirare to favor: the shared entry created by Memnoch, Phractal, and the Big O.
Lest anyone be confused, note that this was NOT a different Mega Jonestown Prime or a different set of God-Monarchs. Some beings are multi-cosmic, and exist across multiple timelines as the same entity. Instead of having infinite copies across alternate timelines, they instead have infinite reflections, infinite ways in which the inhabitants of those timeliness perceive and experience such multi-cosmic beings.
So the inhabitants of this alternate NeSiverse timeline experienced the God-Monarchs choosing the Greys. Unlike in the primary universe timeline, where the favored species (humans) were usurped by the WriterGod and Ancient One, the Greys flourished under the auspices of their benefactors. The first Grey, created directly by the combined powers of Memnoch, Phractal, and Big O, became the leader of the Greys, and was worshipped by his people even as they conquered the stars: for he was the wisest and strongest of them all.
Thus the God-Emperor of Greykind ruled the Imperium of Greykind from Holy Mirare, his legions led by ten primarchs who crushed all opposition under their boots. In this timeline, none could stop them, for the aetherial ultranexus was centered on Mirare, in fact on the Platinum Throne of the Silver Palace.
And when Mega Jonestown Prime returned, the Greys of this timeline experienced its return as landing on the apex of the Mirare's East Pole, directly over the Silver Palace, so that it bathed in the aetherial energies.
And in the dread war between four uber factions that ended in the Beastly time lock, the Greys of this timeline experienced this devastation as the entire East Pole of Mirare being blown to bits, with the sky being full of slag.
Grey Foreman: Dig faster, slaves!
Drow Slave #1: I found a survivor!
The Grey Foreman checks his list of Search Priorities. 'Survivors' is not on that list.
Grey Foreman: Ignore and move on!
Drow Slave #1: But master, his injuries are grave--
The Grey Foreman lashes out with his plasma whip, and the drow slave, and the survivor, are both obliterated.
Grey Foreman: Keep working, dogs! And no backtalk!
The Grey Foreman checks his list again. 'The God-Emperor of Greykind's favorite rubber ducky' is near the top.
Grey Foreman: Excellent work! An extra helping of gruel for you tonight!
Hian Slave #2: Woohoo!
Grey foreman are directing slaves in excavating the ruins of the Silver Palace. The God-Emperor himself and his 10 primarchs survived, but the ultranexus splintered chaotically, and many treasures and weapons were destroyed in the destruction of the eighth of Mirare around the East Pole.
From high above, the God-Emperor of Greykind watches the slowly turning planet from his battle-saucer, an advanced flying saucer fifty miles in diameter, powered by both advanced magic and science. The East Pole is more or less a crater, and there are still flames that haven't gone out. Behind him, in the war room of the immense battle-saucer, his 10 primarchs - all superstrong and intelligent Greys - argue.
Grey Primarch #1: This is an opportunity, how can you not see that?
Grey Primarch #2: The God-Monarchs who blessed us are gone! Forever! How can this be anything but a catastrophe?
Grey Primarch #3: Especially with the ultranexus splintered. Our mages and I have spells blowing up in our faces as often as not, same for any of magitech.
Grey Primarch #4: I concur with Grey Primarch #1, actually. We now are in charge of our own destiny. We are the final authority in our universe now, and not some long-absent deities.
Grey Primach #5: But with the splintered ultranexus, our sovereignty is weakened. Much of our dominance depended our on magical superiority.
Grey Primarch #6: Speak for yourself. We have plenty technological edges, as well as psionics and non-aetherial mages. Plus, no one can deny the greater prowess all Greys possess over the lesser species.
The door to the war room whooshes home, and the God-Emperor's vizier, Fladnag the Gray, comes in. He is a Grey demigod supermage, who wears a bleached white robe that he swears up and down is just a very light shade of gray. No one ever believes him.
Fladnag the Gray: Your Holy Majesty, I have the report you asked for.
The God-Emperor of Greykind, without turning, holds out his hand to the side, and his vizier slips the holo-slate into his hand. The Grey Primarchs cease their bickering long enough to look curiously at their leader as his eyes scan the information on the holo-slate.
God-Emperor of Greykind: Our course is charted, my primarchs.
Grey Primarch #7: Milord?
The God-Emperor turns around to face them. Although the primarchs are taller and stronger than any other Grey, the God-Emperor is even taller and stronger than they.
God-Emperor of Greykind: This is indeed an opportunity for us.
Grey Primarch #5: But what of possible rebellions now that our magic is weakened?
God-Emperor of Greykind: Any planet on which rebels rise up shall suffer... Exterminatus.
Silence falls among the primarchs. The entire destruction of a planet is a brutal and final solution, but it would be extremely effective at stopping rebellions after the first several rebel planets are obliterated.
Grey Primarch #3: And what of our magic?
God-Emperor of Greykind: There is another universe, a timeline alternate to ours, in which blasphemy reigns supreme - a timeline where Greys are not favored, and are scattered and weak.
The primarchs gasp in horror.
God-Emperor of Greykind: We must set this blasphemy right...and claim that timeline's ultranexus for ourselves!
Fladnag the Gray: Also, Your Holy Majesty, you may wish to retranslate our dominion name. In the other timeline, the multiversal 'Imperium' is widely known, and we do not wish that universe's uneducated infidels to confuse them with us, the true and righteous Imperium of Greykind.
God-Emperor of Greykind: Very well. I dub us...the Greyarchy!
The primarchs are dead silent again. The God-Emperor's gaze narrows slightly, and his next words are pointed.
God-Emperor of Greykind: Isn't that a great name?
Primarchs: Uh...yeah! All hail the God-Emperor of the Greyarchy!