The first thing Castiel saw as a human was his siblings falling.
The sky was burning and it was so bright, so hot, a blinding white mess of pure energy, sipping away at the corners of the sky, drowning the world in ash. It tasted awfully bitter - especially since it wasn't supposed to taste like anything.
The sight was familiar. Castiel was reminded of Creation. Down to the core, it was a similar unleash of power, scorching, purifying. Only now, the afterglow was somber. There were no new voices ringing through the air, filling his head with whispered prayers. There was no rushed melody of age, there was no feeling, there was no life. There was no older voice, roaring in a language long forgotten and encouraged to stay so, teaching him "Don't step on the fish, Castiel. Big plans for that fish, you'll see".
There was quiet. There was death. There was nothingness.
Castiel felt the heat of burning grace first. It tingled his skin -really his skin now. He felt small as sparks of warmth danced on his face, on his hands, on his body. His, his, his. The unfamiliar word pressed heavily on the situation and it was suddenly the scariest thing he's ever heard.
Even if his vessel was long gone by the time, he finally understood completly what it meant to be. He took a deep breath, hyperaware of the way the humid air traveled through his nose, filling his lungs. When he exhaled, he felt the breath falling from his parted lips. He listened to the heavy brag of his heart. He was, he was, he was. He simply was.
Castiel wondered idly if the heat was there the last time as well, wondered if the nothing burned as hot as the something. If it did, he couldn't tell. Last time, he didn't, he couldn't feel. Last time, he was an angel.
Castiel watched the world burning until his body started to protest. Until ash got him dizzy and the smell stuck to his skin and his hair.
After that, he turned his back to the sight, to the reminder of his mistake. He turned his back and walked, feeling the earth beneath his feet for the first time.
The transformation didn't happen instantly, as Castiel expected. No, he got to feel human gradually.
Walking, away from the fire, away from his past, the world started setting in.
The heat began to wash away from his body in weaves, making his fingertips tingle and making him all more aware of the warmth rythmically spreading from his chest. The sound was loud, making his ears ring and paining his rib cage with each new movement. It was unnerving, terrifying even, to have trapped inside your chest a constant reminder that you are truly alive, that you have a purpose and you're supposed to leave behind a mark, a reminder; that your time is limited and you have a fate set in stone that will only ever end in death. Castiel didn't like the weight of it. He felt as if it was pulling him down, pressing towards the ground, pushing towards its origins and the need to scream struck him like a lightning. The need to scream that it got it all wrong, that he didn't belong there, that his origins were somewhere else, far, far away from there, where nothing had a feeling and everything was an illusion and no heart, no human heart, could ever comprehend.
However, he didn't belong there anymore.
The thought alone stirred something right at the edges of his mind, something blurry and indecisive, moving like it couldn't quite find its place. It almost felt like a missing piece of a puzzle, like there should be something to fit the gap perfectly, except his mind couldn't register it yet.
But what his new found consciousness couldn't grasp, his body seemed to register as emotion. Castiel felt his eyes filling up and soon enough hot, wet tears started rolling down his face. His fingers moved without thinking, wiping harshly at the running liquid and leaving small, stinging marks down his cheek. He recalled the rare, intimate moments when he witnessed the Winchesters cry and a vague memory of something called "sadness" picked at his mind. Dean described it once to him, one of his many attempts of getting Castiel to understand humanity a tiny bit more - for a split second, that particular name brought a sharp pain to his chest and it took Castiel several minutes before he could properly breath again, without choking on memories and getting caught up in depressing thoughts.
Castiel soon discovered exactly how overwhelming a human body could be, and had he not have been turned into one, never in his rather endless angelic life would he have guessed the constant thrill and never ending movement hidden under layers of skin and muscle. His own body felt like a highly operating machine, constantly shifting at molecular level and forcing reaction that triggered even more movement.
Castiel found that having a human body was, for the lack of a better word, exhausting. Every single fiber or tissue was roaring with life and even the smallest of gestures let loose reactions of all sorts, running freely under his skin and setting all his muscles ablaze in its paths.
The lingering traces of his grace made it impossible to ignore the changes he was going through, stripping him raw of every hope he held into that he won't feel overly aware of his new body.
Nothing seemed to ease the sharp transfiguration of his divine frame being cramped into a limited, physical, human body.
Castiel hated it.
He hated how tight his own skin felt. He hated how loud his own heart was beating, slamming on his rib cage with every step. He hated how air and cold and warmth knitted over his body. He hated how pain shoot so easily through his veins. He hated how much every single cell in his body ached.
He hated his fragility. He hated his vulnerability.
He hated being human.
It has been a long, long time but in the end, in the split of a second, in the blink of an eye, he was harshly reminded what it felt like to be small.
So, so small that irrelevant aspects like weather and walking and breathing and existing hurt.
Castiel couldn't phantom how beings such as humans, who constantly broke apart only to be forced together again as often as they breathed, managed to pull through and develop and explore and create.
In a fit of melancholy, fueled by his personal, newly discovered depiction of humans, he remembered how often Lucifer cried and whined and complained that humans had it easy, that they were favoured, that they were protected and sheltered.
He could almost laugh at the thought and how far it was from the truth.
For the briefest of the moments, he wondered if God knew. If he knew how much it hurt and if he could feel it too.
Castiel left the question hanging over burnt grace and blood stains.
The physical part of being human turned out to be only slightly above bearable.
It's all because he learned.
It was the simplest of things, if he really stopped to think. All little reactions to conditions and expectations.
When it was cold, he were to wear something warm. As a result, the cold went away and his face and hands wouldn't hurt anymore and his cheeks would stop reddening.
He quickly found out that this simple mindset applied to almost everything. It was confusing and inconvenient and stupid.
But it wasn't completely unfamiliar.
He was trying to fit, he was trying to fill up a role, much like he had to back in Heaven.
There were rules he had to follow in order to do so and soon enough the complexity of his own body stopped being a notable impediment.
However, sudden interaction with other humans proved him how little he knew about his new body and the confusion spiked again.
He relied a great many deal on his time with the Winchesters to put together human customs and pre-expected reactions and even conversation topics.
But as much as he forced his memory he couldn't recall any of the brothers even mentioning losing the ability to talk in front of others.
It started suddenly and unexpectedly and Castiel was convinced he simply forgot how to speak. His tongue felt heavy and dry in his mouth and his breathing ragged so much it came out in soft, pained sobs.
He felt weirdly exposed and unsure and his skin felt simultaneously freezing cold and scorching hot, until it broke into a frantic sweat. His whole body was trembling and his eye were stinging with unshed tears.
And he had only tried to talk.
It happened a few too many times and each time it took him hours afterwards to calm down.
And when he did, he only managed to feel pathetic.
A quick meticulous revision over his memories and his own personal observations since becoming human showed him no one else behaved the way he did everytime they had to speak up or everytime crowds were too close and too packed.
It didn't clear anything up to him, other than the fact that he was terrible at being human.
He soon accepted it as some sort of retaliation to his special condition. No, of course no other humans could feel it, since no humans were previous angels, robbed of their wings and grace.
After learning how to steady his breath when it came out erratic and it only ever stopped in his throat, after learning how to loosen the choking knot that formed in his chest when everything got a bit too much and after learning how to stop tears from cascading down his face at any given moment, it all became at the very least decent.
In a way, he thought he deserved it.
In a way, it was all his fault.
No, he didn't know what Metatron was planning.
But shouldn't he have?
Shouldn't he have been more careful, more wise?
That's why Castiel thought he deserved the pain and the struggle and the tears.
He thought he deserved the bleeding, so he accepted the cutting.
He didn't learn how to accept and move on or how to forgive himself.
The scars didn't stop until he got his grace back.
Castiel kept the memories of his physical experience as a human tucked away in the back of his mind. He made sure to remember everything, the pain, the struggle and the utter vulnerability, as a way to strengthen himself, to forge his will and remind him how much he can bear, how much he has overcome.
But everything regarding emotions and feelings was blocked out.
As soon as he regained his powers he wiped away any memory of feeling or emotion.
He can't remember why.
But he has a few ideas.
He knows it was devastatingly, unbearably painful.
It comes back to him in random episodes sometimes, when his grace is shifting and wavering away, and despite the ridiculousness of it all, it's those moments he fears the most.
He doesn't like remembering, not even for a few seconds. Despite it being purely emotion, it never stopped adding actual physical pain, which in return never ceases to surprise him.
Sudden sharp pains, traveling like lightning through his body from where his human heart used to be. They're always paired with dull visuals of his memories.
Scenes that used to play in his mind as simple events during his human time are suddenly ablaze with the remains of what he felt.
It's incredible how much more weight they hold when he can guess the taste of a feeling, how his grace pushes away everytime he tries to remember.
He sometimes feels like it would be a big mistake to force his mind to remember. For the lack of a similar situation, he guesses it might be just as bad as when Sam's mind had to be guarded and sheltered from his time in the Cage. All for his safety and peace of mind from the scarring traumatic events.
Whatever the case, he won't force it.
The random flashes of fainting memories are more than enough to not make him want to remember how the whole thing felt.
However, despite all precautions and hard work he puts into forgetting, he knows it won't suffice keeping everything away.
He is afraid.
There's one scene in particular he is afraid of.
Everytime it plays on his memory loan, his grace seems to work significantly harder, making his mind numb to the point he can't focus. It wraps so tightly around his vision and it tries so hard to move along that Castiel is certain that if he were to remember, it would be the most painful thing he'd ever feel.
He is scared that one day his grace won't be enough to keep it at bay and the matching memory flash will show him Dean, explaining he can't stay, explaining that he has to go.
He is certain that that's the most pain he's ever felt and the fear of remembering makes him clutch onto his grace even more.
Castiel's last thoughts as a human were brief. The promise that soon enough he won't remember, nor understand, the true meaning behind them is what even prompted him to voice them out in the first place.
It was only fitting that he ended his human life the way he started it : tightly sewed with utter misery, regret and pain.
"I'm sorry, Theo."