Equus, a small planet populated by various species the rest of the universe would consider mythic or even impossible, a blue and green ball in the middle of darkness of space…
...the battleground of the gods.
Why? Possibly because of sheer coincidence, possibly because of some higher purpose. No one knows, and the gods themselves won’t say.
Well, that’s not exactly accurate. Two of them, the incarnates of the power of Creation and Existence, no longer exist. Out of the original trinity of Creation, Existence, and Destruction, only one remains.
To explain just a little, nothing can stay as just a force forever, especially when belief is involved. Thus, eons ago, three entities representing the three primal forces emerged. They would have many names throughout cultures they themselves observed or created, but they would eventually become widely known as Discord, the god of Chaos, Life, and Creation, Harmony, the god of Evolution, Free will, and Magic, and Nightmare, the god of Order, Destruction, and Entropy.
After divine wars that had torn galaxies apart, the three gods came to the conclusion that none of them would prevail in a direct conflict and become the ultimate being controlling the destiny of entire existence. With that in mind, they picked a planet not to wage another devastating war on, but to compete with each other.
However, Harmony, whose aspect granted him more freedom and individuality than those of the other two, didn’t put all his plans to rest. In the meantime, though, the gods carefully unleashed their power on Equus, fighting one another in a less destructive way.
Discord created species of creatures, more and more, most of which had no chance of survival on the still cooling planet. That, of course, pleased Nightmare, who eradicated majority of Discord’s creations easily with the help of the environment still not meant to sustain life at the time.
Eventually, Discord, frustrated from the repeated failures, drastically changed his approach, and created the ultimate being… beneath himself, of course. He called it an “alicorn”. Four legs for stability, wings to enable natural flying, delicately crafted horn to focus that most unstable of powers - magic. However, to survive the conditions none of the species before had been able to, Discord had to part with a small portion of his divine power and grant it to the creature as well.
With pure white coat, red mane, and innocence the warring gods couldn’t have imagined, the curious alicorn waded through lava and ash. However, where everything else saw death and destruction, she saw the foundation of new life. She didn’t need a name at first. After all, she was unique in every way, and amidst all the molten death, she began creating the first colourful garden using her own spark of divinity.
That puzzled the other two gods, mostly Nightmare. The new creation survived earthquakes, volcanic eruptions, and toxic gases of the atmosphere. Granted, the plants she had created quite definitely didn’t, but the cheerful alicorn didn’t mind, seeing her burned creations as fuel for new life. Nightmare, driven by her destructive nature, had to step up her game. She had to adapt and explore a previously unknown aspect belonging to her, for the lack of a better word, brother - creation.
Thus, the second alicorn was born, who was supposed to become everything his sister wasn’t. Nightmare made him bigger, male, stronger, and gave up more of her divinity in the process of his creation. He was charcoal black like the endless space, only his eyes were golden, glowing with the power of burning suns. However, since he wasn’t unique anymore, he needed a name. Being Nightmare’s own avatar on yet unnamed Equus, the unstoppable force of devastation and death, she named him after the only place where gods themselves had almost no power, because it was a place of pure nothingness, no creation, no destruction, no existence - Void.
However, what neither Discord nor Nightmare noticed, was Harmony’s endless desire to become the one true god. During the alicorn creation process, he observed and intervened.
Faust, the newly named alicorn of Life, wasn’t completely pure and free of fear and hate. In the same way, Void, the alicorn of Death, didn’t become a mindless raging monstrosity. Thanks to that, Faust saw what Void was supposed to be instead of what he truly was, and kept her distance as well as warned her new smarter creations to flee whenever curious Void came nearby.
And so, half of the planet eventually grew into a bustling garden, while the other half hosted a more and more depressed and lonely alicorn of Death who had no idea why he was the one to be feared without having done anything to deserve it.
Harmony, having tampered with the two alicorns enough, now had a plan. He had been learning all this time about the weaknesses of his siblings. To waylay suspicion, he created his own alicorn - Magnus, the alicorn of Magic. However, where the other two gained the divinity of their creators, Magnus received barely enough to survive on the planet. After all, his maker needed to keep as much of his own power as possible in order to become the one true god. What he did gain was his creator’s intelligence, insight, and freedom, through which he achieved via the use of freely flowing magic powers rivaling the other two.
Having sacrificed the least of his divinity to his alicorn, Harmony was now clearly more powerful than his siblings, and finally made his move. Equus would have been torn apart during the erupting war by the lashing out divinity if it wasn’t for the three alicorns protecting it with their mere existence.
In the end, Nightmare and Discord saw they had to work together to defeat Harmony, and in the final battle they locked him away in the depths of the void, sacrificing a great deal of their own power to keep him sealed.
What they didn’t know about was that Harmony had planned for his own loss.
Just like they sacrificed parts of their divinity to create the seal, when Harmony felt he had overestimated himself he sacrificed his own to create a set of powerful artefacts which he called his Elements, and granted them the power of purification - the ability to disperse and purge otherwise indestructible divine essence. These Elements would eventually find their way to the hands and other appendages of the new races of mortals growing under the watchful eyes of the alicorns.
In the aftermath of the great battle, Discord lost most of his ability to affect the world, and had to contain himself into a small body of his own choosing. On a smaller scale, he retained most of his original power, but if he spread his chaos too far, he would be too weak to keep it going, and natural forces would find a way to end the imbalance he caused. Nightmare came out the conflict much worse, not even being able to create her own host body anymore, and having to possess willing or weak mortals.
The released divinity during the creation of the seal keeping Harmony locked away affected Equus in various ways, granting normal species miniscule ability to use divinity, prolonging their lifespans, and of course… causing wars. The most important thing, though, was allowing the birth of alicorns tied to strong emotions, natural forces, and generally everything connected to the flow of existence. Such as Scream, the alicorn of Lust, who eventually became Void’s partner for millenia, through good and bad, but there are already enough stories and mentions about the two.
All in all, too much had happened since then to recount, but eventually Discord and Nightmare made too many mistakes, became too malevolent, grew too… inconsistent with the life of mortal races, and became the enemy. In efforts to protect civilizations, scholars of ancient texts discovered the Elements of Harmony, and kept using them against Nightmare’s possessed hosts or Discord and his new creations during conflicts over ages.
Several centuries ago, due to constant fighting, Discord and Nightmare eventually grew weak enough for Harmony to be able to destroy his seal and return, drastically weakened, from the void. Some mortals, however, were ready. Harmony’s return got delayed, and his minions destroyed with the help of Discord himself, young alicorn of Hope, and the sacrifices of Void and Scream.
Of course, delaying Harmony wasn’t enough, and the god managed to unleash a plague upon a part of the world known as Equestria, and nearly wipe out its pony civilization. The infected turned into Corrupted, fearsome creatures with unparalleled resilience ruled by their natural breeding and hunting instincts, ruining the sanity of those who came in contact, and turning their victims into more of them. From afar, the hive-like mental structure of the Corrupted allowed Harmony to keep implanting hatred and need for revenge on ponies, the species which had ruined his plan of return before.
However, ponies still prevailed with the help of Nightshade, a young pegasus mare who against all odds survived the infection, retained enough sanity to gain control of several Corrupted as their new hive queen, and eventually secured some living space on the surface for ponies who had been forced underground by the Corrupted.
Nightshade’s sanity didn’t hold forever, though, and she eventually embraced her Corrupted nature, thinking about her new kind not as a killer plague, but a new species with its rightful place in the world. Thankfully, despite her subjects and power spreading, she considered other races to be part of the world as well, and with the help of those who had stopped Harmony’s return before, she found the source of Harmony’s remaining power, and freed her kind from his malevolent influence.
Harmony did lose his weapon, but he had more tricks up his metaphorical sleeve. Based on his findings with Corrupted, Harmony discovered an earthpony mare broken by the loss of her foal, and possessed her, changing her body over time to become an indestructible killing machine. There was no one who could stop her rampage after being filled with an amount of Harmony’s divine power rivalling the primal alicorns.
Almost no one. Feats of unbelievable insanity and love brought back the alicorn of Hope from the dead. Under his leadership, the unthinkable happened, and a group of mostly mortals managed to track down old research based on previous attempts at resisting the gods, in the end finishing the lost project and crafting weapons capable of fighting them on even footing.
Finally, Discord and Harmony fell, returning only to natural forces they used to be in the beginning of time. Freedom for the mortal races was within reach. No longer they would be victims to whims of gods, and their fate would be in their own hands, hooves, and, of course, other appendages.
However, they completely miscalculated how overwhelming Nightmare would be without the divinity of her two counterparts suppressing her own. They can't have known, no one had ever been in such situation before.
Faced with Nightmare, one true god at full power, the heroes stood no chance. Their experience and training, their own knowledge plus that of those who had tried to resist before them meant nothing. Ruthlessly and brutally, Nightmare killed them all, and continued her plans.
Yet, despite the only remaining avatar of primal force being that of Destruction and Entropy, Equus still exists as far more than a ball of silver ash. For how long, that is a question on the minds of the few with the knowledge of what happened.