A/N: We all have a pretty good guess about you-know-who, but only tonight's episode will tell for sure (or maybe not, the show could toy with us some more). Anyway, here's a piece I just had to get down. Huge thanks to Miyth and 29Pieces for beta reading and providing input that helped shape this.

Disclaimer: Don't own Supernatural.

"Favorite Son"

The screams were unrelenting. White-hot lightning speared Lucifer's very essence and forked through Castiel, the barrier erected by the archangel to keep him locked down offering no protection. The fire consumed the two angels, melting away one's dominance and control to the point that Castiel felt the rawness in his vessel's throat from them both screaming themselves hoarse. There was no refuge to be found in unconsciousness, either, for Amara's power didn't allow for it. Castiel was flayed; Lucifer was shredded. And the cycle repeated. Over and over again.

"Why doesn't he come? He's supposed to come!"

"Told you…" A wheeze. "Not to…count on it."

At some point, Castiel felt his grace start to crack. Amara was channeling her power intentionally so as not to kill Lucifer, but the surges that diverted away from the archangel's core skewered Castiel's instead. And he had been in a lot weaker condition to begin with. Fractures split through his mind, his soul. Awareness of who he was and what was happening sifted through the fissures like a sieve.

Lucifer was likely in too much agony to notice, not that it would matter. Should Castiel die, the vessel would become wholly the Devil's, just as it had when Jimmy Novak died and departed for Heaven. Castiel, unfortunately, would not have the same, kind end. He felt pieces of himself slipping away, much like when Naomi had carved into his head and systematically gouged out his memories. He would be dismantled. A dying dwarf star consumed in a neighboring supernova.

"Stop."

The searing burn ceased, and Castiel collapsed in on himself. He could feel Lucifer shaking in the vessel, but at this point it was distant, the rumble of an earthquake miles away. Castiel's grace quavered, and he watched trickles of himself dribble out like sediment shaken loose from a flimsy foundation.

"Look who finally showed up."

"Yes, you have my attention."

Castiel shuddered. Grace crumbled like glittering stardust through incorporeal fingers. Maybe he could float away after all, like dying embers into a night sky, away from the prison of a mortal shell, of pain and gravity. If he could manage to ignore the throbbing and raw burns pulsing through him, it was almost a peaceful kind of death.

"I knew you would come for your favorite son. Does he still shine as bright as you made him to?"

A bolt of lightning forked through him, and Castiel felt the vessel's back arch, mouth gaping wide as light exploded from within. His grace spasmed, and Castiel screamed along with his brother.

The torturous fire cut off abruptly, leaving both angels gasping in utter shock. Castiel couldn't move aside from the twitches running through his essence. He felt himself growing heavier, which was strange—with all the pieces he was hemorrhaging, shouldn't he feel lighter?

"You will not touch him again."

"You're pathetic, brother. Here I've been laying waste to your beloved Creation, but it's only for your precious Morningstar that you finally show your face."

"You never did understand me, Amara."

A static pressure built in the air as two opposing forces crackled against each other. Raised voices echoed like thunderclaps, followed by the whomp of explosive power. Castiel tried to curl in on himself further while Lucifer squirmed around him, agitated about whatever was happening outside.

And then one storm vanished with an infuriated snap.

"Father. I'm…surprised you…came. Didn't know…" A cough. "You still cared."

"Be quiet."

Fingers plunged into his chest, stealing Castiel's breath once again. This time was almost worse, as something doggedly dug into his core and wrapped itself around Lucifer. The archangel tried to retreat, to hide, but there was nowhere to go. Lucifer screamed his murderous rage, which reverberated down through Castiel like nails on a chalkboard. This was finally the end. Lucifer would be destroyed, and Castiel along with him. Expendable collateral. Likely no one knew he was still in here.

The Devil was yanked out, and Castiel suddenly found himself thrust back into the forefront of his vessel, eyes frozen wide open and body violently hitching for desperate breaths. An arm snaked behind his shoulder blades, and Castiel felt himself being carefully lowered to the ground. As a hand cupped his head so it didn't crack on the cement, Castiel gaped in bewilderment at the figure leaning over him. He couldn't see the man's features, for the brilliant glow of Lucifer's grace cast him in a blazing silhouette.

The stranger turned to look at the archangel writhing in his other hand. "I'll deal with you later."

Lucifer's high-pitched whine cut off as he was shoved into a container of some sort. Castiel couldn't tell, for his vision was spotting with white starbursts, his lungs seizing and chest burning. Deep inside he could still feel his grace splintering under the strain.

The figure turned back to him, and Castiel hiccuped with fear. No, please. He was nothing, no one. Just ignore him…

Gentle fingers touched his brow, and a warm breath of air washed over him. Power seeped into his skin and down to his grace, ghosting over the raw wounds and catching the leaking fragments. Slowly and with great care, Castiel felt the invading presence begin to weave the pieces back together, as though it knew exactly where each one fit.

"I know I've put you through a lot," a soft, almost remorseful voice uttered. "And I know you've always tried to do your best. You have and always will be a son after my own heart."

Castiel's chest juddered, his physical body still in shock from all the trauma. His mind was having difficulty processing as well. What was happening? What did they want?

"Shh." A hand settled over his heart, and the one on his forehead moved down to cover his eyes.

Castiel jolted in alarm at the sudden darkness, but the presence beside him sent a soothing echo through his mind.

"Just sleep for now. I have you."

And he did.