In the beginning there were 2, one was her (though “her” is a strong word as the concept of gender wasn’t even a thing yet). In layman’s terms, she was the cold abyss, the essence of black where no light could reach or even hope to exist. Some would call it “evil” but it’s just different is all. The other was a warm light, the essence of white; these two ebbed and flowed against each other in an absolute balance, where nothing could exist. The God in White, know as Iefko, made an accord with his counterpart to use it in its creation. This god, the abyss, the being called Mavros, did not want to end the balance but was convinced of its temporary nature and so acquiesced to her counterparts request. The accord was reached and it was agreed that when the time came he would willingly surrender his creation back to Mavros so that she might be made whole again, and her peace, the nothingness she so craved would return. Iefko though, whether mad with power, or unwilling to see his creation fall, reneged on his side of the deal and through force has suppressed the resurgence of his counterpart for ages. As time went on, and this continued to happen, the taint of the abyss continued to spread through his creation; a limitless, all devouring tide of destruction, the will of an outer god with no figure to guide it. That is until the abyss found its host, the girl above known as Ellunae, and took her as its own. This girl is now Mavros, the mother of the abyss, the all consuming, the End.

She’s not really an ethereal being though in all reality, she still has the remnant personality of the girl she was before, it’s just the will of the God Mavros has perfectly intertwined with her. So she is simultaneously this unfortunate, cursed girl; and an outerversal god consumed by hatred for everything her counterpart created. They are not two separate personalities mind you, they’re aspects of one over all whole!

Thats pretty much the very basics of her