[This here message is being written by me on an iPad 4 that I did not remember to exist but somehow unearthed, while I am waiting for repairs. Still cannot log into Discord. This post is not crucial to the plot, does not directly follow from previous posts, should not interrupt the narrative, and will probably be moved down and/or changed later.]
[EDIT: Have repaired my phone! This was mercifully fast.]
ON THE GREAT GAME OF THE GODS
It's all really the fault of the Old Ones' and Necrontyr.
Khorne's overall domain is incredibly unappealing. Yes, living sentient things struggle and fight plenty, but nearly universally, they would rather not. And by the time that their civilizations' warp presences become large enough and accumulate enough to start birthing Chaos Gods, normally, this really wouldn't be the focus of their emotions.
Well, in The Galaxy, that did not happen, because the Old Ones were too stingy to share information to save the lives of Necrontyr - which would have cost them nothing - and Necrontyr were too offended to respond to that by anything that's not starting a gigantic and endless and utterly merciless galactic war of mutual extermination.
On the accumulated psychic background created by this war, Khorne, the God of Struggle and Frustration and Conflict, was born, as the very first God. Everything that happens further down is his fault.
Chaos Gods can be fairly described lowercase s superintellegences, but Khorne's s is written in an especially tiny font, and he really isn't a good player in the Great Game. His domain continues to be largely unappealing and narrow. His demons and greater servants represent the least efficient possible approach to combat - kinetic melee weapons. Where the Greater Daemons of other Gods can conquer a typical planet in days while acting alone, a Bloodthirster need months.
His advantage lies in the echoes of sheer slaughter in the ancient war, and more importantly, in being the first mover.
Because after his birth, he had eons without any competition at all to reshape reality to his will, among other things intentionally making the Warp become more hostile for the living overall to intensify struggle, and multiplying the wars between peoples, turning civilizational engines that produce the war machines to grinding halt and decay, producing a low-boiling equilibrium of constant infighting, and driving people to resignation.
Upon this background was born the second God, Nurgle, of Stability and Decay and Acceptance. Do those domains sound naturally very adversarial? Not really. But Khorne was the dominant force in the warp, twisting everything into conflict, and influencing the formation of the new God. This would be a God of enforced acceptance and decay, of hostile stability. Thus, Nurgle's primary method became disease.
Nurgle is far smarter than Khorne, but is also that much less motivated, being of Acceptance. His domain is more attractive in essence, but repulsive in implementation. His main advantage lies in physics. Without taking Warp into account, decay is the easiest thing to cause and foster, and every system wants to reach a stable equilibrium. The energy economy of bacteria, viruses and fungi is far more efficient than the energy economies of slaughter, knowledge-accumulation, or recreation, reliant on complex systems to feed them, on vast arrays of energy collection and communication/regulation lines.
Tzeentch, of Change and Hope and Pursuit, was born in absolute spite of Nurgle and Khorne. Now he, he had no shortage of either motivation or intellect, and he used them to gather even more intellect, and then used that to gather more resources and power and broaden his domains, because if you aren't doing that, what are you even doing? He was an excellent player, and tied the other two Gods combined. However, in a world governed by strife and decay, knowledge already had some awful psychic baggage of associations - of being used for ill, and worse, of being unearthed rather than discovered, and worst of all, an extremely strong association of being a madness, and a very contagious one.
Tzeentch knew full well how terrible that was for him. Secretly, he despised dwelling in a giant transcendent library, and not in a giant workshop or laboratory. To the extent to which Gods and not popular beliefs shape demons, he tried to offload as much of his madness from himself as possible into separate minds - which is why his minor demons are so insanely erratic. Yet, a somewhat mad and erratic God he remained. His dominance was in many ways the golden age - Eldar empire reached a peak of psychic sophistication and Humankind created the most powerful mage to ever walk the land and then comparatively rapidly rose to incredible mastery of technology. But his dominance was a status quo, and He was erratic enough to wish change even to a status quo extremely beneficial for him. He could have subtly prevented the appearance of any new gods, and slowly grow to be able to slay the old ones. Instead, he plotted the Age of Strife, the Fall, and Slaanesh. Just to see what would happen.
With Slaanesh, of Joy and Desire and Art on board, Tzeentch's dominance ended, his scepter of power shattered, him being reduced to about 3/4 of his former power, and now easily outfightable by a coalition of three. Being birthed chiefly from very, ahem, interesting (to Tzeentch, who subtly pushed things to limits) ways to achieve Joy and Are and fulfill Desire, Slaanesh is rightfully widely despised.
Even then, Slaanesh's domains, fundamentally, are very attractive. People sometimes call her a God of Excess, but if you (dare to) ask her, excess implies there being such a thing as too much joy, and that just doesn't make sense. If given a choice between worshipping disease and despair, endless deadly combat, obsessed planning, or whatever makes you happy but less ethical, people overwhelmingly choose the latter. She is impulsive, selfish, sadomasochistic, irrespectiful of life, never bothers to ask, and treats her people quite badly (outside of pumping them full of pleasure), but she still has the most allies both active and passive. Though the newest God with the least time to accumulate power, her natural power accumulation rate is the highest, as al people worship and seek joy to some extent - that's what Joy means.
It's really fucked up that it took that much time for a God of Joy to form, isn't it?
Well. In a different universe with Warp, where Milky Way's first Civilization isn't fucking terrible, and where it doesn't get randomly thrown via a warp storm into a terrible hellhole, the first God to be born would be a God of Light. Of Joy and Desire and Art, but applied in such a way that is in accordance to all the values pursued, at once, for the shared benefit of everyone. Her offspring would perhaps be better called Aengels instead of Daemons, and her seat of power would resemble not a palace but an amusement park, or a festival, or an entertainment virtualspace, or a museum, or a psychic chorus. Other Gods would be born under Her influence. And the first of those would be the God of Progress, of Hope and Change and Pursuit but turned toward constant improvement, living in a cosmic laboratory, not a library. For Progress is a direct derivative of Light, needed to further it's expansion. And then, when civilization will hit a ceiling, when all the possible low-hanging fruit will be picked, perhaps after some other Gods are born as well, will come the God of Harmony, of Stability and Decay and Acceptance, but as stability of good things, and acceptance that there may be a ceiling on them getting better, and a decay of such efforts, residing in a beautifully cultured garden. And then finally, much much later, perhaps near the end of the world's fuel, should that not be averted via Warp, perhaps after Civilization's fall of some or other terrible cause, perhaps just of painfully slow accumulation of emotions, after dozens of other Gods, will come a God of Survival, of Struggle and Frustration and Conflict, against adversarial conditions more than against adversarial people, in a bunker that is a refuge of absolute safety.
Alas, alas, alas.