The forest was wide and lush. Down, on the earth, beneath the twigs and leaves the world was veiled in eternal shadow, but up in the tree tops…
Castiel watched as the emerald sea move with the wind, the rustling almost overwhelmingly loud, forming waves for him to ride on. Somewhere a bird took flight. It was beautiful.
He had always loved his father's creation. Before there were deciduous trees there were pines and ferns, and before that algae and weeds. Before the birds came the dinosaurs, and before them fish, and before them countless worms and squids and sea snails and arthropods and anthozoa – diverse, colorful forms of life that are difficult to relate to for humans, even if they are all mortal life and therefore family.
Brothers.
Castiel remembered the two billions of years before that, when all life still existed of a single cell. They were much like modern protozoa – their 'souls' are to a human's what a human's soul is to the Morningstar's grace – but already Castiel was fascinated by them. They were so small compared to everything he knew, so irrelevant, but so different to what was before. They were not just the molecules they were composed off – like the sea around them, like the stone, like the air, like the magma contained within the earth, like the planets and the stars his father had created before – but neither were they just a spirit like Castiel, his brethren and his father. They were a combination of both.
And much like the planets and the angels – like anything his father had created – the Earth-bound spirits, insignificant as the were, prevailed.
Before his father had created life, the spiritual and the physical worlds had always been separated. Atoms, electrons and neutrons adhered to the rigid laws of physics while grace was moved by the boundless will of spirits. It was not that they could not interact with the physical world – his father was a spirit himself and he had created it – but they simply existed on another plane of being, they were no part of it and it was no part of them. They had simply enjoyed watching and manipulating their father's creation – playing with balls of ice and balls of fire, the energies of wind and lightning, flying through wormholes and studying imploding stars. They raced and fought and hugged and laughed and sang together. The galaxy was theirs to explore, and all of them were together.
One thing the humans did not know about Heaven – if they even believed in its existence – was that it was not created for mortal souls. Long before the first man ascended to Heaven, it was the realm of the angels and their father, one out of many such realms for many different deities and entities. It was the angels' very own presence that had created it, and that was upholding it still.
That had been one other fascinating thing about the first earth-bound spirits: that they were mortal. All that came before – the rock, the salt, the water – had been created to exist forever, until something else sought to destroy it. The mortals were only temporary: eventually their molecules would inevitably dissolve – and when that happened, their spirit was simply gone. Just like that. No angel had smitten them, no titan or giant had crushed them to nothingness, when the molecules that their physical body consisted of were even temporally displaced, their spirit ceased to exist, and even putting the molecules back together could not recreate the spirit. Castiel should know, he'd tried to recreate his father's creations many times over the course of his existence: pulling their bodies apart and putting them back together, using his grace to spark new life in them, but it would never stick. Once the spirit was gone, it stayed gone. Castiel now just guessed that was the nature of spirits, mortal or not.
That was the way how things had been for a very, very long time. Spirits, mortals and molecules all coexisted – interacting with each other, but each on their own plane. And it was peaceful in Heaven – of course they battled, there was a reason why Castiel was created a warrior, but they battled the Titans, Apep, demons, the Leviathan, sometimes God commanded them to slaughter millions of mortals at once and once they'd gotten involved a long-winding conflict between the gods from Olympus, the dwarfs from Svartalfheim and Zhulong, the Red Dragon. But never had they fought each other.
Not until the first human ascended to Heaven.
Still Castiel did not know whether their father – or the deities of the other realms – meant for human souls to become immortal after they die, or if the most advanced species of all mortals developed that ability themselves, but the angels had not expected to see a soul enter Heaven. It was Jabel that had found the man, and thinking she was simply correcting a mistake she smote him.
It had been the logical thing to do: all mortal souls disappeared when the body died, why should this one be different? However, their father had been furious at her digression. The mortal she'd destroyed was a human, and the humans had always been their father's greatest creation – they were the ones he'd been working on since the beginning of time. God told the angels that they should let the humans' souls enter Heaven, guard them carefully, and love them as they loved each other – as they loved their father.
Jabel said she did not know this, that she had been ignorant but now regretted her action and begged her father for forgiveness. But their father stroke her down.
So it had happened: Lucifer was not the first fallen angel, as was written in the mortals' holy books, it was Jabel. Only she barely reached the Earth: the fall burnt her wings and shredded her grace and she lived a mere fifteen years on Earth in agony until their father allowed Inias to bring her the mercy of non-existence.
Not long after that, Lucifer rebelled, angels fought angels with righteous conviction and Hell ensued.
And Heaven was never peaceful again.
Castiel spread his wings and felt out the currents of the wind. Bird wings were created after angel wings, but in contrast to birds angels didn't need air to fly. They simply went. But if he wanted to, he could let the air affect his feathers as if they were made out of actual molecules, and try to ride the wind.
But the days of fun and play were over, and he had a mission. So Castiel took flight.