When a human child is born, their soul is shattered into bright gleaming pieces that scatter to the winds.
It's not really their souls, of course. More like echoes of their souls, a manifestation of each human's essence that slips into the physical body of another. A piece of themselves that they recognize in others.
Castiel thinks it's one of his Father's most beautiful gifts to humans. It's a light on their path, a way to lead them to those people who will bring the most love and joy into their lives. He understands in a distant way that a human's soul carriers may also bring them pain, regret, even despair, but that pales in comparison to the radiant glow he sees within a human when they meet one of their carriers.
There are angels that begrudge humans this gift. There are angels who believe that the Father gives too much to humans who appreciate His love too little. There are angels who crave for themselves the depth of feeling humans have for one another.
There are angels that fall to have it.
Castiel has never spoken about it with any of his siblings. Those considering falling would not find much sympathy with an angel like Castiel and his siblings know this. They know that Castiel is one of the most devoted, the most faithful. He may not always understand his Father's plan or why his existence is so different from the humans his Father loves so well, but he understands his duty and takes joy from performing it.
It is more than enough for Castiel.
Which is what makes it all the more shocking when he is struck full in the center of his being one bright morning with an enormous chunk of a human's soul.
It knocks him off his flight path, sending him tumbling into crystal sands of a vast celestial beach. His wings tangle together and Castiel has the brief thought that he is glad none of his brothers are present to see his moment of terrific clumsiness. The weight of the soul piece is staggering. It is more substantial than Castiel could ever imagine and for reasons he doesn't understand, it feels more real than any other substance he's ever touched.
Once he's landed on his back and the world has stopped whirling, Castiel is able to sit up and examine the soul piece in his hands. It blazes, vivid and intense. A snow white orb with tendrils of cold flame flickering around the edges. It's the closest Castiel has ever been to a soul piece and it fills his chest with terrifying awe. With trepidation, he strokes one finger down the side of the piece. It pulsates and shivers, clearly recognizing Castiel's presence and it reaches for him, tendrils wrapping around his hand and up his arm. Insistent. Claiming. Castiel feels it begin to merge with his own essence. He is filled with wonder. How can a human soul hope to blend with the powerful grace of an angel?
His confusion and fear send him to his feet. He shakes the sand out of his wings, thinking hard. The answer is clear. There are only two angels he can trust to lead him in the right direction. He gently tucks the soul piece into the front of his gleaming white cloak and takes flight. Within seconds, he finds his two siblings in the city, discussing what sounds like the next batch of orders for their garrison.
"Anael," Castiel says quietly. He feels a sense of guilt over interrupting his superior, but the look on her face is welcoming.
"Castiel, child. What are you doing here? I thought you were flying," she says, her tone indulgent. Castiel knows he is not the only angel that enjoys soaring through his Father's creation, wings stretched wide and the gift of wind fresh on his face. But Anael thinks of him as her special younger brother and finds his quirks amusing.
"I was. Something happened though," he answers. To the side, Uriel makes an inquisitive noise, though Castiel can tell he is not terribly interested in the proceedings. If there are battle orders, Castiel feels certain that they command most of Uriel's thoughts.
However, when Castiel reaches into his cloak and draws out the soul piece, he suddenly receives the full brunt of his siblings' attention. The glimmer of the soul piece brightens the already shining room in which they stand. A surprising flash of pride that this soul could improve even the surroundings of Heaven itself cuts through Castiel.
"Where did you get that?" Anael asks sharply. There is something in her voice that frightens Castiel, that strikes him hard, nearly as hard as the soul piece had earlier.
"It came to me," Castiel explains, voice shaky. "It...I think it knows me."
The disdain in Uriel's voice is clear when he finally speaks. "How could a creature of dust recognize you?"
"I don't know," he answers honestly. None of this makes any sense to him. He looks to Anael, hopeful as always that she will be able to explain and order the world for him. Instead of the reassurance he seeks, her expression is hungry, her eyes glued to the soul piece as if unable to look away.
"It's so large," she breathes. It's true. Castiel has studied the phenomenon of soul pieces more than any of his brothers, delighted as he is by the concept and though he doesn't truly understand much about it, he knows that this piece is significantly large. This human will only have a very few soul carriers in his or her life. It makes the responsibility heavier, the confusion greater. Castiel has never even properly met a human. He has no idea how he is supposed to bring joy and love into one's life.
Anael reaches toward it, as if to touch it. Wrongness screams in Castiel's being. Without thought, he jerks away from her, tucking the soul piece further against his arm, protective and defensive. The message is clear to Anael. She seems to remember herself and backs away, expression clear once more.
"Castiel," she says and her voice grows in intensity, the way it always does when she is about to impart extremely important information. "This soul piece. It's a soul mate piece."
It's the first time in his existence that Castiel feels true shock. He hadn't seen, hadn't really understood what he holds in his arms. But now that she's told him, it becomes obvious. The possessive nature of the piece, the way it claims him with a sense of entitlement that Castiel's never experienced before. In an instant he goes from being one of a multitude to a single entity, an individual that will command the love and devotion of a human he doesn't even know.
He lacks the understanding to grasp what is happening to him.
"It must be a mistake," Uriel declares, dismissive and once again bored with the situation. Castiel doesn't enjoy the brief flare of indignation that borders on anger he feels at Uriel's words.
"Our Father doesn't make mistakes," he says, tensing at his own ugly tone. "You know that."
"Perhaps." He looks down at Castiel and though Castiel loves Uriel with his whole being, he sees that he'll never truly understand his brother. His devotion to their Father is true, of this Castiel is certain. But his attitudes can be so disrespectful.
"But how can you expect to mate with a human?" He spits the word 'mate' as if to reject it from his body. "You can't be expected to defile yourself by lying with a human. If you didn't destroy the feeble body with your magnificence to begin with."
Castiel frowns. "I don't think the Father would send me to love a human who couldn't withstand my presence," he says carefully, though in truth, he has very little idea what the Father had been thinking when he sent the soul piece to Castiel.
"Maybe you should go to your human," Anael says, her voice blank. "It may help you understand this situation more fully."
Castel considers her idea. Uriel doesn't understand the purpose of the soul mate piece. He thinks all humans approach their soul mates with lust in their hearts. But Castiel knows better. There are a great many humans that wish to copulate with their soul mates, yes, but there are many who find their soul mate piece in a friend or relative. The true meaning of a soul mate is simply the one person without whom a human doesn't truly feel complete. It's not a given that every human will even discover their soul mate piece.
This human will though, Castiel thinks as he turns the piece over in his hands. Already it has begun losing shape and form, dissolving into Castiel's being. Very soon, it will be a part of him and that's the moment that it finally strikes Castiel.
He won't feel complete without this human either.
But angels aren't given to these feelings. They are not built for it. How can Castiel already feel at a loss without the presence of a human he's never met when he's never been anything, but content with his lot in life?
"Perhaps I should," he finally says to Anael's suggestion.
"I could go with you," she offers. The blankness in her tone is spiked with sudden and uncomfortable interest. "I should very much like to see the human who can mould itself to an angel's grace."
He should yes. He should have no problem sharing this moment with Anael as he's shared every moment of his existence with his brothers.
"No," he says. "I shall go alone."
Without an explanation or a pause to hear her response, Castiel tucks the piece away once more and takes flight, his wings echoing in the long marble hall.
Castiel has never been to Earth by himself. His garrison has fought many battles on the earthly plane, but against demons. He's rarely had the chance to see through his eyes to the physical world instead of viewing through the spiritual lens. It's just as beautiful as he remembers from the few snatches he's allowed himself in the past. Truly a masterful creation, a display of his Father's immense creative talents. Castiel could spend endless years watching it evolve around him, but he has a purpose and so he follows the bright trail he senses towards the human. It's not difficult to follow.
The human is rather obvious.
Castiel finds his human in a large room filled with boxes. In each box there is an infant child. For a brief moment, Castiel is puzzled. Their number is too great to constitute one single family, yet Castiel can't imagine why humans would group their offspring together in a room, unsupervised. He sees a door off to one side and when he stretches his senses, he hears several adult humans talking to one another about the children. That's when Castiel finally realizes that this building is some kind of birthing center and the adult humans must be specially trained in dealing with newborn humans.
He has much to learn about human life.
Following the trail once more, Castiel flutters down in front of one box in particular. The child laying in it is similar to the others in the room, but Castiel instantly sees how this child will always be different to him. The soul piece in his arms shudders in proximity to its original master. To Castiel, it feels akin to the love he holds for his Father, but again, there is something different. Something he's never experienced before and therefore can't identify. But it is pleasant.
Castiel allows the physical realm to fall away and peers into the child's soul. At first Castiel is so enthralled by the purity and intensity of the soul that he can't discern any details. The passage of time, strictly enforced on Earth and lightly felt by angels, falls away completely and it isn't until a woman appears in the doorway that Castiel's attention is broken. Infant humans can perceive an angelic presence without damage, but many adult humans cannot, so Castiel has kept himself cloaked. While he waits for the woman to leave, he peers at the child's soul without losing himself in its beauty.
He sees the place where the soul piece broke off. It will be an empty void within the child unless Castiel is nearby. An emptiness the child will be able to tolerate, may not even feel at all until it's filled and then the human will always notice its absence. Along with Castiel's piece, he sees other empty slots, all large. Two have already been filled and Castiel assumes these belong to the child's parents.
There are two pieces still within the child, meaning that they belong to humans not yet born. One piece is smaller than the rest, but brilliant and warm. A short but important relationship.
The other piece is unnaturally large. Bigger even than the piece Castiel carries. He is fascinated by the dormant strands of emotion threaded through and over it. It is not a mate piece, but its importance obviously equals Castiel's. He doesn't mind. After all, since Castiel will not be able to enter into a sexual partnership with the human, the child will have to find that partnership elsewhere. It's possible this piece belongs to the child's future spouse. Castiel briefly entertains the notion of watching the child growing up and getting married, having children as well and it makes Castiel feel rather warm.
When the woman finally leaves, Castiel reenters the mortal plane and focuses his attention on the child's physical appearance. He is male. His skin is pale and pink. His cheeks and limbs are round and fat and for some reason that makes Castiel smile. He has no frame of reference for human beauty standards, but he thinks the boy presents a sweet image.
He notices a round white card at the base of the box and peers closely at it. The words, "WINCHESTER, DEAN" are printed on them in English.
"Hello, Winchester Dean," Castiel says.
All at once, every child in the room awakens. Some begin crying while others merely gurgle and squirm, grabbing for their own feet. Castiel frowns. His human's eyes open as well, but he doesn't cry or smile or do anything, but stare at Castiel with big blue eyes. Once again, Castiel finds himself caught by the child, unable to think much beyond the strange unique love growing in his chest. He barely remembers to cloak himself when several adults burst into the room, frantically searching for the source of the noise which woke their charges.
Castiel's human begins to cry the instant Castiel disappears.
His usual patience wears thin waiting for the adult humans to finish settling the children. When they leave, he appears again. Winchester Dean reaches for him, tiny arms flailing. Castiel doesn't want a repeat of earlier events, so instead of speaking, he leans over the box and cautiously presses forward the tip of one wing. The child catches the end, small fingers wrapping around the edge of one single feather.
That's when Castiel notices that the soul piece is entirely gone, merged completely with his grace.
He is caught forever.