To understand what "it" is we need to back to the time of it's creation.

Legend has it that before the multiverse that we now live in was created a single unified one existed,

and there lived a race so advanced they had achieved near omnipotence.
The race worshipped perfection but their main reason for their piety wasn't belief but the shared fear of all things unpredictable and uncontrollable, in other words they feared chaos.
Driven by that fear they used their powers in a crusade to create a perfect world, certain that cleansing every corner of the universe of chaos would unveil their utopia.

But they failed, even even when their nation spanned every corner there was chaos still remained present.
It was then the truth came upon them, it was revealed that chaos itself was the very reason for their existence, so as long as they existed no perfection could ever achieved.
Thus they concluded that the only way to their salvation was to eradicate everything, only a total emptiness devoid of anything that could affect it could truly be perfect.

And so they created a god, an artificial being born without feelings or emotions, an empty shell with the power to bend the world with its will and with the only purpose to destroy it... And so it did.
It destroyed the matter that built up the world.
It destroyed the energy that powered the inner workings of the world.
It destroyed the souls and spirits that gave life to inhabitants of the world.
It even destroyed time and space
In the end all that remained was the god itself floating in an endless void.
The gods purpose was about to be be fulfilled, the only thing that remained to be destroyed was itself.
But just as it was about to execute it's final command a moment of hesitation stopped it.
As the thoughts or killing itself passed through it's mind a response from deep within echoed throughout it's very being, and for the first time it felt fear.

As the gods will was reality, so was the fear within him and thus his mind gave birth to a a being.
A monstrosity embodying the force of chaos and the fear thereof.

Within his mind the being was twisting and turning, a black mass growing, devouring, corrupting and threatening to escape and undo the work of the now deceased race.
Unable to defeat it, the god sealed it away in a separate dimension, a new universe, all within his mind.
There he took its body, its voice and tore its existence asunder, leaving nothing but a faint shadow of what it once was.
But not even a god could truly erase it, and for every moment the creature was allowed to be it grew and influenced that around it, for such is the nature of chaos.

Bound by both destiny and duty the god of a dead people was thus condemned to spend its eternity sacrificing his body to subdue his own creation.

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Gaaah! this took so long time but here it is, my first reference sheet!

This is my character who doesn't really have a name, but I call "him" chaos as that what he is.
Note that this isn't my "sona", chaos is a OC from a world building project I'm working on. I just like drawing him! x)

I've tried to include a nice summary of the character in the reference, and some lore above but as always I'm more than happy to answer any questions~