To call them siblings was only an approximation. They were siblings the way a pair of kidneys are siblings. Twins the way eyes are. But even those comparisons lent too much of a degree of identity to either of them, back when the dream realm had been whole.
A closer way to think of them would be to think of the way albumen and yolk made up the whole of an egg; it was only upon their separation that either would even realize they were different, and that components of a thing were not themselves the entire thing. They were not necessarily meant to ever separate, but that did not change the fact that they each had their own distinct properties once they did, by virtue of the individual reasons for their creation.
Their separation was not painless. It was slow, at first, and came from internal conflict of the living realm called "Dreams" who could not handle how it contradicted itself.
It was perhaps the first instance of a thing realizing its heart and hands did not agree with each other. The mortals eventually figured out how to handle that particular struggle without tearing themselves into dueling polarities. But the original apotheosis had not really had anything to go on yet.
Apotheosis. That was the word.
The realm of Dreams lay sprawling beneath the layered skins of all others, touching life and light and death and dark and ferality and invention with utter indiscrimination. Dreams were the door to which all would pass, so vast was it that concepts like good and bad and love and loss were to it less than nothing.
But that did not stop the skirring things that were laid bare for Dreams to know in whole and beyond from deciding how much concepts mattered to them . And in the end, it was them who decided what truly mattered, for they were the first to form vocabulary so that they could lay claim to things. Their tongues moved in the name of their dreams, those names given in the same breath, regardless of whether or not they understood that. They told stories. They prostrated. They screeched, and they died, and they prayed and they loved and they bred and they hungered and they stared, eyes wide, minds open, receiving dreams through as direct a touch as magic could possibly execute.
Their worship was what gave apotheosis personification. For they loved so deeply, that it had to change much of what it was so that it could properly love them back.
They loved the inspiration of dreams. They loved how dreams instilled within them drive, and ambition, and hope, and imagination. Dreams became their guiding light, that gentle, glowing-warmth characteristic of life that made it sometimes seem so magical.
And so the Radiance of Dreams grew wings to nestle those she loved beneath.
There is a reason mothers warn their children not to fear so very many things. Fear is a form of worship. The intensity of effort devoted into a thought is no less powerful when it comes from a place of hatred, or of sadness.
And these wild, beautiful creatures were capable of such sadness. Grief, and pain, and terror turned out to all so profoundly consequential that they could each change the very nature of their dreams. Even the simplest of creatures could be utterly dominated by fear. And fear could drive any and every one of them to cause yet more of it. Horrors committed in a place by those despairing souls rippled, and stained, and changed the landscape of minds and homes and people for as long as they existed, and could remember.
And so the Heart of Dreams warped and shifted to accommodate their suffering, and it became where they stored their nightmares.
But for all that fear was powerful, it was a scattered thing. It could not compete with the direct worship and potency of a name. The Radiance grew more and more into a thing all its own, endowed with eyes, then even a form. Their love grew it a crown, and it came to fancy itself all-mother. And so She was.
And as she grew, she pulled away from that other side of her. The one that her children so reviled and feared, even if they did not understand what it was, that it was its heart, her heart. It was what hurt for them. It felt the pain dreams might sometimes cause them, because loving them meant knowing their anguish. The light of dreams shone for them, and the heart of dreams ached for them.
But the part of them, the Light, that loved them all for how they loved their dreams, did not want to see them hurt. She thought it senseless torment. Why must it be this way? Why must they be allowed to suffer, and why must we feel it, now that we have been made into a thing and things that feel ?
And her Heart told her: It is what they are. It is how they dream. To live is to lose, we have seen how this pattern repeats in every little life that loves you. They cannot be what they are without knowing what it is to suffer. It is so much of what they are. Their young hatch screaming and choking for breath. We must know all of them.
And the Light said: I can know all of them. There need not be dark if Light touches all. They need not be alone. They only need to love me, and I shall protect their dreams. They shall know only what I deem good for them.
And so further and further apart did the Dreams split, as the Light began to ignore her heart, and the Heart began to beat its own rhythm within those who did not give up their personhood to Her completely, in exchange for a hivemind life of beholding Her radiance.
All the while, their Heart still ached within their vastness. She railed against it as an incomprehensible flaw. Nothing that felt this way should be worshiped. She entertained the idea of strangling it until it ceased beating, so that it might stop influencing her, might stop forcing her and her wayward children to feel such unpleasant things.
And then the first creature to willingly succumb to the embrace of the nightmares prayed at a gruesome altar of his own making.
He was once one of the Light's tribe, long ago. He was exiled for his rejection of their enforced unity. He was a deeply troubled soul, named by his hissing ex-kindred as Grimm, for they would only identify him as a bad omen and nothing more.
He prayed not for vengeance, or for love. He prayed only for oblivion.
The Heart broke for him.
So full was the Heart of all things aberrant and abhorrent, that its embrace would only naturally come with horrific consequences. It also did not have the sheer power its glittering counterpart had amassed. But she, with her complacent flock of light-blind, would never accept such a wretched creature as the one who now prayed to the only thing that would listen. The Heart would beat its last with the extinction of lives like his, ones that were lived raw and unpadded.
The creatures that now loved the Light were no longer the same as those who first ever dreamt. And while the Light was more than happy to write those generations off simply as the necessary precursors to her perfect children, the Heart, bleeding as it was, could not forget them. Their pain and their fear could not be forgotten. They were what sustained it, now.
This, maybe, was the discrepancy that finally defined them as separate beings. If not this, it was what the Heart did next that sealed the deal.
The Heart made its very first servant an offer.
He would have his oblivion. He would be free. He would be emptied of all that made him himself.
And that shell he left behind was to be filled with the essence of all nightmares. He would be their incarnate, and the Heart would be their furnace, so that all the horrors of civilizations past would be consumed to make room for the next ones. Their pain would be put to good use, feeding the Heart and Grimm's kindred forevermore.
It was much to ask of one shell. The Heart knew all that madness would burn it away eventually. But feeding upon their nightmares would lend it enough power to craft new vessels in his image. It would see sons born while fathers burned for them, and each would inherit his memories. He would be once and future King, innumerable times over.
That was to be Grimm's curse for his destruction.
And so the first Grimm accepted the terms, and stepped into the Heart's open wound. Eyes wide, mind open, while it burned him alive into a charred shape as fearsome and unrecognizable as his misery had made him to himself. This form was the final gift the Heart gave to its despondent child, though he who had walked into the flame to receive it would never know. For itself, and for what stepped out, it kept only his name.
And what stepped out was not Grimm, and it was not Dreams. At the same time, it was both. It was fractured, and it was a different kind of whole. It wept. And then it laughed.
And so He was Grimm.
It did not take the Radiance long to notice the celestial gore that now marred their shared realm. She'd not ever truly shared it before.
" Why have you become?!" She cried. "What have you done ?"
Her Heart, no longer her's for how she'd forfeited it, spoke from the flame-dried mouth of its chosen vessel.
"I have chosen love and fear both, dear Light. For the dregs of little life discarded by the ‘ All Mother ’, I have created a Dread Father. One who shall weep with them. One who shall laugh for them."
"You mutilate us. With this fissure, you have finally divided our realm between radiance and sickness . The dreams you allow to fruition are poison ."
"I allow nothing that does not come naturally to them. I co-exist with life as it moves. Our realm changes with them, not the other way around. You manipulate their dreams, you meddle with their minds for their love. But you never needed to. For specializing your reign, you've made it so fragile, and you never needed to."
"As always, you tell me only nonsense."
"They adapt," he went on. "They always have. Can you , anymore? Can you substist on anything less than the entirety of minds devoted to you alone?"
"They need me."
"You have made that so. But even when you fill them with purpose from the moment they are born, they are still doomed to die, and the next born are not the same. How does a being without a heart cope with loss?"
"Take your loss. Take your doom, and take your death, and your Nightmares, and stay away from my children."
"I'll not touch them. Time will tell what might."
And so the realm of Dreams was split in two. She kept the parts full of gold, and hope, and love, and secrets. He kept the parts that did not like to face the light, and that trembled and smoldered until they either erupted into consuming inferno or fizzled out into ash.
They ruled their sibling realms separately, and stayed far apart. Their realms were no longer compatible, for the bastardizations they'd become of what had once been far simpler aspects of a whole. They were themselves, now.
The Radiance had her gilded utopia for a time. The love she encouraged from her children was built upon a foundation of impressing them with dazzling light, and the gentle luxury of blissful ignorance. It was enough to make a heart grow cold and wanting. There was no passion. There was little of anything at all.
And that is why when a being arrived who could shine a light of his own, and with all the brilliance and zeal of a voracious, pronged leviathan, Grimm was not surprised that her children were ensnared in his thrall with an unthinking willingness to take all he might offer. And so quickly. She didn't take well to it, of course. She'd only ever existed to be loved in the first place.
As for Grimm, he actually had no trouble finding lost souls who'd eagerly worship the scarlet of his flame. So very many were abandoned by what they once loved, or believed about the world, or else they saw it all destroyed and were left with nothing. So many godless runaways, and violent sorts. So many nightmares. So little in the way of smiles or laughter in their lives. Their willingness to forfeit those lives is what attracts them to the Heart, for it knows their plight well, for whom it now beats.
And so Grimm invents a circus of the damned, for a place full of song and spectacle and dancing pyres of spiraling fire for all the runaways who might find themselves irredeemably lost. And he offers them all a deal.
"If you seek to wipe your slate,
Have none that you might call kin or group,
Don the mask and light your lantern,
Come and serve in Grimm's Dread Troupe."