Disclaimer: Don't own the universe, just playing in my corner of the sandbox.
A/N: This little fic was written with me wondering what happens to angels who get blasted away by the angel sigil and wanting more Castiel and Lucifer interactions. Enjoy and stay warm :)

In a glass coffin

He hates it here, this place between places.

It's a world of banishment, where the void of nothingness counters the violence of wishes, curses and prayers. It's a painful barrier to pass through, like running your entire body through a shredder to reach the nothingness beyond the looking glass. And there at the non-existent, physical ground, where everything's mirrored at the base of your feet, pools of rippling liquid glass shimmer and melt turning orange and folding in on itself when thoughts shoot through like tiny meteorites raining from below instead of above.

The first time, a year in human terms a mere blink in his, he was able to stand on that smooth surface. Wait with a seething Uriel at his side as the shoes of his vessel scoffs black marks against the pristine surface where the world is laid at their feet in a hazy fog. Uriel laughs as a prayer of a man being possessed blasts a hole of molten liquid. It's close where Anna banished them.

It's good enough as they fly through the hole that reseals itself minutes later.

The second time it's worse; for he is fighting, throwing a tantrum Bobby would say as Dean sends him shattering through the glass. It hurts and burns every feather and ounce of grace. And as he staggers into existence on falsely fragile ground, his anger builds and builds. Anger towards Zachariah, towards Gabriel, towards God and Dean, but mostly towards himself for being so foolish...for having his faith placed in the one person he starts to see as a brother.

So when that first hole emerges with a hiss, he takes the plunge. In the middle of a smoldering desert of Djibouti where heat waves intensify his rage Castiel closes his eyes holding the anger in, waiting with his feet planted on sand melting into glass till he hears a single prayer flashing like a neon sign. He takes off in a roaring tornado.

Third time, he screams. Screams for eons as his wings and grace are ripped and shredded before melting into a hole as another thought surges through him. The hole he forms within himself closes before he can make it through while the door way to the warehouse seals up as well.

He's stuck in this middle ground of a place between places, caught up in the curtain, trashing and screaming in utter agony as he tries to break free. But he can't. He's not strong enough this time. His siblings gaze down at him dispassionately. Then his sister turns her eyes to the right where a hole forms from the peppering of the cries of family being attacked by vengeful spirits. It's in California so they disappear through the hole in blinding flashes of comets, leaving ashen trails of dust in their wake.

In the wake of abandonment, Castiel thinks clearly for the first time, is hopefully Sam was able to free Adam and Dean had said no. Just for once, Castiel prays, just for once let this be a victory.

Then the glass cracks and shifts, scrunching and tearing him, the last thought running through his mind is of a human saying: that the third time is always the charm.

Liars.

This becomes his existence for ages or is it minutes? He crawls and squirms, finds himself pinned and frozen. The glass becomes him, morphing him into whenever and whatever existence it wants. Past screaming himself out of rage and pain, he curses and snarls and throws a rant of pent-full frustration and crushed dreams and new confessions in every language he knows. Once the tears start flowing, he finds himself laughing with ragged gasps as he tries to pull his one free, broken wing towards him while the other is barely left in its socket, stretched into the glittering beyond.

He can't help but think he's like one of those pictures painted on the ceilings of old churches. And as that thought flashes through his brain, he hears Dean's voice muttering about how he can dig that stuff while Sam would smile warmly at him.

It's how it starts, Cas reflects back when the tears are dried up and now slivers of glass on his frayed cheeks and his voice is all but gone as twisted fingers trace the jagged, bleeding scar of the sigil on his chest, that he's going mad.

Dean and Sam bicker loudly in his head. Sometimes, though, he hears Michael in Dean's voice banishing Sam into the Pit. Other times, he hears the snarls of Michael and Lucifer having conversations in their vessels, like the old days before the First War. He hears the screams of humans, the orders of angels and the giggles of demons.

Otherwise, he hears nothing at all except for mindless screams as the glass shifts and torts anew. Then he feels a burning in his upper back, and knows by now another curse is coming through him. He's gotten to know the difference.

Bracing for the impact, the unexpected happens. Piercing whiteness scorches his waist as long fingers sink deep into his ravaged body. With one powerful yank, he's thrown free of his coffin, the glass barrier shattering around him while he plunges head first into darkness.

It hurts to breathe in this dank air, lungs straining against the soft confines of his chest. Blinking, he squints to take in the dull orange light a tiny lamp off to his side. Through the blurriness, he can feel pins and needles shoot down limbs he thought he would never feel again.

It scares him this joy, this once-borrowed heart pounding in his chest inciting a series of wrenching coughs. His shoulders thump against a soft mattress, chest burning from the carving as the cloth of the blanket scratches over it. A presence hovers behind his back, wings draped in a bloody mess over his back.

"Easy, brother. Breathe."

He does.

The next time he comes around, he feels rested, grateful that the shards of pain is gone. But he's bone-tired, lying there on a soft bed where the thrumming of crickets is a welcomed noise. The comforting weight of his vessel warms his flickering grace yet the energy is not there. Pushing himself slowly on shaking forearms, Castiel realizes through a haze the only clothes he has on is his pants. Arms trembling, sweat starting to gather on his forehead, he rolls gently to the side biting back a hiss of pain as his aching wings brush against the soft grain of a wall.

Blinking, he glares at the blue painted walls of some bare room. His bandaged chest heaves up and down and for split second everything goes white. When he comes too again, he fears he's back in that glass prism, but that rainbow existence isn't before him. Instead a dark haired woman with a morphed face lunges at him with a long silver dagger.

"I'll kill you this time, you impotent sap!"

Instincts kick in as the angel raises one arm to block the dagger as his other reaches up to encase her wrist, struggling to keep the blade from touching his chest. Meg bears down on him, pressing him further into the bed and wall, wings twitching in agony, snarling and cursing in the guttural language of demons. "I'm gonna gut you like a fish, I don't care what-"

The snap of a collar bone signals the appearance of a simply dressed man with dull blue eyes and blond hair. The only thing out of the ordinary is the blistered hands and face. Lucifer fixes a cold fury onto the demon screaming and withering in his grasp.

"I warned you," he speaks softly but the room rumbles, the wind whipping at the tiny window. He narrows his eyes and the tiny lamp explodes as Meg is burnt of existence.

He's afraid to move, to even breathe. So Castiel sits quietly cross-legged on the lumpy mattress, eyes staring endlessly into the dark room. Lucifer left after the Meg incident, hauling the vessel's body out while muttering a sincere apology. And that was that.

It scares him this new form Lucifer projects to the world and unto him. He remembers distantly a Lucifer shining with pride and confidence, his voice booming with clarity.

It's nothing like what he is today. Maybe it has something to do with Nick, or maybe it has something to do with being locked in the Pit. And if anyone should know how the Pit can change an angel, it's him.

The door cracks open, light spilling into the room. Lucifer walks in carrying a fresh wad of bandages and what appears to be a steaming cup.

Castiel's eyes speak his wariness, throat not ready yet to speak. Lucifer smiles gently, setting the mug down on the table and the broken light bulb flares to life. "You are not yet up to strength, Castiel. This will take longer to heal."

Lucifer settles down next to him, stretching out with bleeding knuckles. Castiel flinches away, wings dragging themselves brokenly over the blanket. Lucifer chuckles, eyes shining with mirth not at all like the coldness of before. "I will not hurt you. I must say you astound me with your...methods. Quiet the genius; I wonder if Dean appreciated that."

Castiel's face darkens and Lucifer leaves it at that.

It becomes a custom, routine enough for Castiel to no longer flinch at the caresses of Lucifer against his broken body, his vast awe-frightening grace giving him a rush of connection he didn't know he missed till now. Sometimes, he'll lie on his stomach Lucifer running healing hands down his shattered wings, sliding each tiny bone and feather back into place.

As he trembles, Castiel doesn't cry or utter one scream and Lucifer smiles with something akin to pride. His angelic voice gone for the time being makes him mute in this world. And afterwards, Castiel finds himself nibbling on the food Lucifer brings him.

Other visits, he's asleep for days on end yet Lucifer's presence is calming after the terrorizing nightmares of the glass world.

And sometimes...

"Zachariah is dead." Lucifer's calm voice is like a shot in the dark. Castiel is sitting on the edge of bed tonight, holding a glass of water in his hand. In front of him, Lucifer is staring out the window content to watch the world bustle outside.

With the Apocalypse going on, Castiel can't help but wonder that it's a bit odd seeing Lucifer take his sweet time with everything, as if there isn't a deadline. It's like he doesn't have a care with the world.

Blinking, the devil tilts his head to lock onto Castiel's confused face. "It's hard to say what happened, considering Michael was nearby."

Something akin to hope dies in the younger angel's eyes and for a split second Lucifer finds himself wanting to hold the little angel close to him.

Castiel walks carefully over to the window, barely has the energy too, shoulders hunched forward enough not to drag his sensitive wings on the wooden floor. The bandages are gone but he remains shirtless, Lucifer saying it would be good for the wound to get some air. He doesn't say anything, can't really because those words are spinning like a windstorm in his head.

"Is it true?"

Castiel turns to gaze over his shoulder where Lucifer is leaning in the doorway.

"Did Dean kill the Whore?"

Castiel tilts his head down and returns his gaze back to the window where across the street in a small suburb, a father passes a football to his son while the mother is cheering from the sidelines. They have no clue of the Apocaplyse or that Lucifer is their neighbor.

"I'll take that as a yes then."

Lucifer's gone and Castiel can't help but feel he's betraying everything he's stood for. But there's a growing void in him since he walked into that warehouse whispering to him not to fight anymore. Dean's gone, Sam is probably dead and his father doesn't care. So why should he?

"Why did you join them? They caused you nothing but pain. No thank you, no outwardly concern or friendly gestures?"

Castiel tries to pretend he's asleep as Lucifer sits on the corner of his bed, watching him intently. He tries not to shiver as the older angel's grace runs soothingly down his aching back.

"Did they even know? Did Dean ever truly realize the extent of your sacrifice? Not only were you dead little brother, but for you to come back...you're an abomination, not natural."

Castiel tilts his head deeper into the pillow.

"Dean preached about how he can't kill his brother and the two fought to save each other. Did they know that you have betrayed your family to fight for their cause which is all about preserving their meager family? Did they understand that you have killed your brothers and sisters multiple times? I mean how many?"

"13" he thinks and under each blink, he can see their faces and eyes full of disgust and disappointment.

A hand lies gently on his leg, "They just used you, Castiel. They didn't know that this is killing you slowly, that as an angel you seek family and bonds. You're not an archangel, where we can survive this isolation with our grace intact. But you, this exile is a cancer and being human is the agonizing death that awaits you."

Castiel's frame tightens as a tear leaks down his cheek.

"They didn't understand, Castiel. But I do. Like I said, we're the same you and I and if I can give you back your grace; it's just a small bonus."

The hand tightens around him in something that Castiel has seen Dean do many times to Sam when comforting the younger Winchester. It's a brotherly affection and Castiel soaks it up and dares to believe in Lucifer's words every since he rescued him from that prison.

Because like he said, he understands when Dean never did. Perched on the bed, Lucifer grins.

He flaps his wings lightly, the pain becoming a mere ache that will never truly go away. Blue eyes fall to take in the pink scar on his chest. It's the best they can do, even under Lucifer's tender watch. Thankfully the lines are broken, so it can never be used again accidently, not like Castiel wants another visit back into that glass coffin.

Lowering the wings back down, he drops the white shirt and begins to button as his strengthening grace curls in his chest. He can't let Lucifer know how far he's been healing himself, because he's afraid that then this twisted world will be gone and he'd have to face a world where Dean is Michael. Maybe, he could visit Gabriel and hide away in his own witness protection program as a pagen god like Dagda, the celtic god of wisdom.

Peering out the doorframe, Castiel tries to gaze over the simple wooden railing to where a group of demons are lounging about. There's too many for him to take on and he can't trust his wings just yet. Not to mention it seems a bit disconcerting that Lucifer didn't even try to put up wards to cage him in, which makes him wonder if the archangel himself is keeping tabs on him even when he isn't present.

And it knaws at the back of his mind the sudden interest Lucifer has in Dean. He heard the accounts, from Sam, how Lucifer would ignore his brother, even after shooting him in the head. And Castiel could only tell Sam that despite Dean's status of being Michael's vessel, Lucifer also knows that harming Dean might not be the best way to persuade him.

Thus, this sudden interest makes Cas fearful. Even if Dean's Michael, Lucifer bringing up the points that Dean, a mere human killed the Whore isn't suppose to happen. Every instinct in him is blaring loudly that something is amiss here.

In a blink of an eye, Lucifer is before him face blood splattered and blistering. Castiel stumbles backwards, back colliding against the cold wall. He tries to keep his face blank, but the terror leaks out of him.

The devil glides into the room and with a flick of his wrist, slams the door shut. "Gabriel is dead." His voice is the cracking of a glacier, the rage and grief rattling the wooden frames. "You should have left him to rot in the Pit, Castiel."

The world stops spinning and Castiel finds himself frozen. No, not Gabriel, not the only angel out in creation that could provide some help...some support outside of Lucifer. He might not have known the archangel well, but still, to know that he was out there, that there was a potential ally. That once he finally joined them, Gabriel could be the brother Castiel desperately needs in teaching him how to interact with humans.

Gabriel wasn't Lucifer, but now with no rogue archangel, Castiel can't find a reason not to stay with Lucifer. At least with the devil's attention on him, Sam would be safe...if he was still alive that is. The mere thought of Michael killing Sam pops a dam of grief for his friend. No wonder God and Dean left him. He's a failure but most importantly he's a traitor, just like the angel in front of him, who's seething and lost to the world.

Both stand there grieving for a brother. But Lucifer is the worse, his grief mounting and mounting. Castiel bows his head, knowing that this isn't going to end well with him, but he doesn't care. Maybe Lucifer can finish what he started in the warehouse, so he doesn't have to be around to see the world burn.

"...should have left him to rot..." the tense of the sentence bits hard, shocking Castiel out of his stupor. It didn't sound past tense, but more like Dean could be... Blinking, the angel flicks his eyes upwards onto the decaying man seeing the answer in his brother's eyes.

Dean.

Lip curling upwards, Lucifer snaps punching Castiel hard into his temple sending him colliding into the wall. Plaster rains around him from the newly formed dent.

Lucifer glowers over him, wings stretching out in their full, singed and boney wonder. "If it wasn't for Dean, Gabriel would have stayed on the side lines like he normal did!" A swift kick to his stomach and Castiel hears the snap of a rib blood spilling out of his mouth mingling with the gash on his eyebrow.

"But no! Gabriel listened to that veil cockroach and stood against me leaving me no choice but to-" Lucifer's voice hitches, his guilt over killing his own little brother with mischievous eyes always eager to learn new tricks to play on Michael flashing before him. It's those innocent eyes fueling Lucifer to grab a tight hold on his brother's left shoulder, hauling him up, oblivious to the searing stench of flesh and the voiceless scream as Castiel twists and pulls.

Punch after punch, the devil hammers down on this creature who made his vessel hidden from him, who fought on the side of a hunter who shouldn't be doing the things he's done because it can only mean one thing and it infuriates him. Lucifer doesn't care if the trust he's been trying to build, of those seeds of doubt he's been planting are now being washed away by blood and oozing grace. All he cares about is inflicting pain, of letting go just once instead of maintaining this sickening façade.

And as Lucifer rains down his wrath and grief, Castiel curls deeper and deeper into himself, cradling his burned arm to his chest, where instead of a hand print, three talon lines bare the clutch the devil. Yet through the mind numbing agony, all he can think of is Dean, how he is still alive in this dark revelation.

Oh how it can only mean one thing. Dean said no.

Dean said no and is with Sam, the faith of a brother rewarded. Its Dean, Castiel realizes in a loud gasp as another rib snaps in time with his leg that killed Zachariah. Dean who held the blade of an angel and did the one thing no mere human should be able to do.

The hunter's changing, the rational part in his mind whispers but into what he doesn't know. Maybe he's becoming the righteous man again? Or maybe, Castiel's grace wraps around him as Lucifer slams him into the space between the bed and nightstand, plate and glass shattering on the floor, maybe it's something more. Maybe it's the mere fact that they are walking the right path.

Sam's strained voice replays how it was God that put them on that plane and brought Castiel back to life. That Gabriel, the reluctant one and so bent on getting the two to become their vessels, picked the side for humanity of all things. Hope swells in him burning away his depression as Castiel tucks himself into the corner, his back partial to Lucifer who stands before him, raising his blood-stained arm.

Gabriel died for humans and Castiel can't let that death go to waste. Even if Dean will never fully understand his sacrifices or if Sam will give into his anger, Castiel can't give up. He jumped head long into this mission knowing the full implications and it's about time he stops hiding from it.

"You're nothing but a grunt, Castiel, a mere ant. So why is it that our Father brought you back but not Gabriel...why not him?" Grief driven rage has made the devil mad, blind to his arrogance and mistakes. "I'm tired of this war and this rotting corpse. Now tell me where is Sam!" The quiet threat to make Dean suffer as he is suffering plagues the room in a swarm.

Turning to Lucifer, face battered and bruised but already starting to semi-heal, Castiel can't help but smirk. Lucifer's right, he is a mere grunt. But for a grunt, he's been to Hell and back, survived multiple exorcisms, fought against highly trained angels, faced Raphael twice, time traveled with passengers by himself, dodged detection when hacking into Heaven and faced a Horseman and lived. Lastly, he's searched this world forward and backwards, dodged the enemy of both Heaven and Hell.

All in all he's learned to be adaptable and absolute at the same time. He's found a balance in this spiraling chaos.

Faith in himself tickles at his glowing blue eyes causing Lucifer to furrow his brow of shedding skin and blood. He's faced this tainted brother once before and lived and he will do so again. "No." Castiel's voice is a mere ghost, scratchy and weak from not being used but its conviction is unwavering. The will to fight is back in him. "I'll never join you."

Lucifer's face flashes with disappointment before his rage is back. Raising the red hand, Castiel feels the prickling of an archangel's grace rising to smite him.

With a twist, Castiel slams his left palm onto the sigil he's painted below him on the wooden floorboard. Familiar whiteness swells into the room, pushing at Lucifer, trying to expel him into the world beyond the glass. Yet, the devil is strong, feet scrapping at the boards to stay put as his hands claw at the air.

Face bent downwards, Lucifer tries to peer beyond the too bright light, screaming, "Castiel, don't do this or-"

But Castiel opens his majestic wings lined black and blue with bruises. Grabbing his clothes and coat, with one final burst of power from the sigil to hide him, he flies into the abyss.

He doesn't know how long it's been, zig zaggin back and forth, laying false trails to throw himself off of Lucifer's war path. He shields his presence so deep; that the angel needs to hitch a ride from an elderly man in order to reach his destination.

Dressed back in his old clothing, the blue tie hanging with that comforting weight around his neck, Castiel stares out of the window soaking in the brown hills of South Dakota. The trench coat smelling of a strange mixture of human and nature lulls him into a peaceful state as the old man hums along to some old country classic crackling through the radio. The clanking of the car relaxes him as he heals the last wounds on his body. The marred hand print of Lucifer remains though as well as the gash on his temple. Two more scars and yet he can't find the energy to be worried over it.

He's tired but he's no longer drowning in misery or pain. So he finds himself blissfully shocked into a state of content, at least for the moment.

The first person he spots walking up the dirt driveway is a small man in a suit leaning against the banister, eyes flicking up to him. A wicked smirk dashes across his features as his eyes blink black for a second. "Well, well, aren't you a delicious sight."

Castiel merely glances at him, not surprised to see this demon here. It is the end of the world and the drastic push to the finales.

The screen door groans open, slapping against the frame. Sam's tall form towers over the small demon, "What are you doing out here, Crowley?" There's a learned distrust at the demon but the weariness and anxiousness is new.

Crowley rolls his eyes, nodding his head towards the angel, "Just having a friendly chat with our new guest."

His British accent is full of smug goading. Sam jerks his head up, body poised for a fight when he pauses; face falling open at Castiel's ragged frame. "Oh my god...Cas."

He only takes on step forward before a blurry green form blazes past him in a whirlwind of anger, concern, regret but most of all relief. Castiel soaks it all in, every single thing that screams Dean: his strong gait, the slightly dip of his shoulders, fingers flexing between a fist and openness but most of all those green eyes baring a soul he knows all too well.

Dean halts a few inches away, eyes zeroing in on the gash, "You'll need stitches for that." The voice is short and clipped, anger tinging the edges.

"I'm fine." his own is dry and cracked but no longer a ghost.

Without warning, Dean flings himself over the slightly smaller man and presses him tight. "You stupid son of a bitch," he whispers into the angel's ear, apologies exploding from that one simple sentence.

And in that welcoming, Castiel realizes as he takes in Bobby's happy eyes from the doorway to Sam's beaming smile and lastly Crowley's muttering something along the lines of 'lost lovers' as he skims on his phone that even if they never truly understand or get each other, that this right here...this is worth it, even if it means the Devil's wrath and him becoming mortal.

A tight squeeze and Castiel finds himself grunting from the sharp bite of his burn. "Dean."

"What?" mutters the hunter, it seems like he isn't about to let go any time soon.

"Personal space."

Dean's frame tightens as he pulls himself away jerking backwards to lock eyes onto that familiar pale face as if maybe this is an imposter. Castiel merely gazes back, taking in the stern eyes no longer lost to the dark but almost shining with an inner light that makes him blink in awe. It's a familiar glow, something he thinks he's seen before but can't place it.

"Cas."

"Hm."

Dean takes in the achingly familiar tilt of the head, knows it's really Cas just a little bit more banged up than usual but still Cas behind those ancient blue eyes and sighs, "Never mind, let's get you patched up."

Swinging his arm over the angel's shoulder, the two walk side by side back into the house, Bobby already berating the angel for his suicidal tendencies, Sam remarking he'll get the first aid kit and Crowley sneaking in a few pictures of the whole shebang.