"Castiel!" It echoes across the battlefield once called Chicago, the second syllable ringing desperately amid the graveyard of fallen skyscrapers and steel spires. It used to be such a magnificent tribute to human progress, their buildings and imaginations soaring to reach even Heaven. He remembers the erecting of the Sears Tower and how he wept, for there was nothing left to accomplish, nothing more awesome than the tower stretching into the sky. It lies in pieces now, shattered like felled chess pieces. He tries not to think about it; it is a heartache he can't afford now.

"Castiel! Castiel, are you able to move?" Small hands prop him up and he gazes into the young face of Zophiel. "Where is it, Castiel? Where is the Instrument?"

It is windy. He can feel it ripping at Jimmy's coat. His coat. It hasn't been Jimmy's in a long time. Dean has taken to calling him "Rent-to-Own", much to Castiel's annoyance, especially when they are pressed together in bed.

He blinks and shakes off the daze he has fallen into. "Dean. Where is Dean, Zophiel?"

Zophiel's lips part around baby teeth, the front two missing. It's a warming sight on such a cold, crushing morning. "He still fights. He still possesses the sword. Mikael has given him control, but he can't withstand much more."

Oh, thank God. Dean.

"And Sam? His brother? Has he been overcome?" If Lucifer found a way to Sam, managed to rip through the miles of warding to find the prize at the heart of them, then it won't matter if Dean still fights - his soul will die when his brother does.

"Not yet."

Then there is still time. Castiel grits his teeth and pushes himself up. The slab of displaced concrete on which he'd collapsed is drenched in his blood. Zophiel stares, perhaps in worry, or perhaps because it's the first bloom of color she's seen since coming to this ash gray world.

"Castiel," she murmurs, pushing air through the gap in her teeth on the S. She has a lisp.

The wound dealt to him by Hadraniel flares with a sharp, wild pain and spills more blood down his side; the tickle of it against his skin is an additional discomfort. The street swims sickeningly before his eyes, and Zophiel's tiny hands steady him when his legs falter and he staggers. It hurts; he can't escape it by healing. The jagged bits of broken Enochian weaponry have fused to his flesh, preventing it from knitting back together.

"I am fine." He even sounds convincing; another trick learned from Dean.

Zophiel doesn't push. "Do you have the Instrument?"

Here, you take it. You're the biggest blowhard I know. Take it up and end this. Gabriel had pressed it into his hands and helped to hide it, grinning all the while through a mouthful of blood. Think of me when you and Boy Wonder have all that victory sex. Or not, because eww. Later, bro.

Flinching away from the absence of Gabriel's Grace, he forces out, "I have it."

"On you?" He shakes his head, the movement bringing something up in his throat. "In you?"

Castiel coughs and spits onto the asphalt. It's hard but brilliant, octahedral in shape and twisted into a lattice. He recognizes it immediately. His Grace is crystallizing inside of him. "It is with me. I will be able to use it."

The worry he reads on Zophiel's face flattens out into grim determination. It is the same expression she wore moments before the battle began, when she first saw their opposition approach and wearing the seal of Heaven. She has always been ready for war, even before there were wars to fight. Dean would like her efficiency, her hatred of demons.

"Don't turn around."

He can feel them. They are countless in number. "How many?"

"It is Omiel's garrison. It seems he has sided against us. How fast can you reach Lucifer's vessel?" She tightens her grip on him.

Castiel tentatively stretches out a wing and bites down on a scream. Hadraniel's blade pierced through it as well. He is down to two now. "Fast enough."

"Liar." Zophiel pats his arm. "Your human will be very angry."

He smiles. "Not if I save Sam."

"You may be surprised." She draws her blades and steps away from him, effectively dismissing him to focus on her new opponents. "God speed, Castiel."

He bursts into flight before the Omiel's garrison reach for their weapons. It takes a great effort to pull apart the continuum and pour his essence through every dimension, slipping through them as fast as he can. The pain from his wing is unbearable but nothing compared to the wound in his side. His Grace is hardening within him, leeching from his limbs to pool at his core, everything heavy and cold.

He can't fail. He promised Dean he would do all in his power to keep Sam from being taken, and he has never broken a promise to Dean. He doesn't intend to start now.

The sky rips apart and spills him onto the edge of the last ward, nearly on top of Sam, who sits naked and soaked with holy oil. Breathing through the pain, Castiel watches through weak eyes as Lucifer pushes his way through the fifth layer without care for the symbols burning with fire.

"Cas! Cas, fuck, what's happening out there? Where's Dean? Oh my god, what happened to you? Are you okay?"

Castiel looks up where bright flashes illuminate the black clouds. It looks like a thunderstorm. It is a storm: the final tempest before a decision is rendered.

But where is Dean? If Lucifer is here and not battling Michael, what has happened to Dean?

His stomach rebels and he drops suddenly to his knees, mouth filling with saliva, gut rolling and pushing up. Something sharp drags over and slices his insides, the soft tissue of his esophagus - the same one that swallowed pie at Dean's insistence but only yesterday - splitting like gossamer. He vomits blood and Grace, the hardened crystallites spilling out in a crimson-soaked pile.

"Oh, god, Cas! What the fuck? Tell me what to - Cas, he's coming. He's almost here! What are we supposed to - Cas! Cas, get up, man!"

This is what death is.

So, I was thinking… you know, when this is over, you don't have to go back right away. You could stick around for a while, maybe do the Christmas thing for real. Me and Sam can show you what it really means to live. Well, I can. Sam has no life. But… I can show you anything you want. How to make eggnog, how to decorate a tree. I'll teach you all the songs. I want to show you. Stay, Cas. I know I have no right, but… I want you to stay. When it's over, stay.

Castiel blinks away tears and forces his body to cooperate, to push through the pain, to expel Gjallarhorn from within him and into his hand. He has to save Sam. He promised. And if he can muster up the breath then he can finish this. He wants to stay. He wants to learn the songs.

"Dean," he whispers, "Merry Christmas."

Lifting his chin and meeting the gaze of Lucifer, his beautiful and terrible brother, head-on. He brings the mouth of Gjallarhorn to his own and blows.

It halts.

Lucifer is pulled back down through the earth, the lower dimensions, to be encased until a new opportunity arises.

It stops.

It is done.