Epilogue:

Castiel knew something terrible had happened, moments before he felt Lucifer die.

Lucifer didn't always let him know what was going on, and to be fair, Cas didn't always try to hard to find out. Discovering God, their father, was using Chuck as a vessel was something. How long had Dad been using him a vessel? Was he there when Cas died the first time, keeping the archangels away from Dean? Was that why he brought him back? Part of him was afraid to know, because his fury would be beyond measure if his Father had been there the whole time and did nothing, even though he could have saved Sam, Dean, him, the entire world.

The funny thing? He and Lucifer agreed about this. Lucifer actually joined him at the kitchen island in the Winchester's kitchen, and discussed it. The only common ground they had was disappointment in their Father. It wasn't a detente that lasted long, but that was okay with Cas, as he hated having anything in common with Lucifer. Still, Lucifer had told him a couple of story about Dad Cas had never heard before, and wasn't sure he'd ever repeat, unless he wanted to disillusion the other angels completely.

He was aware of the fight against the Darkness, and what a poor plan it was. But there wasn't much else they could do, so he was on board. Even Lucifer had to give the Winchesters that. Between a terrible plan or doing nothing at all, they always went for the terrible plan. Lucifer called it "almost lovable idiocy", and hey, at least it was a kind of nice thing to say. From him, at least.

Cas hated talking to the angels. He was so ashamed in their presence, enduring their hostile stares. He knew why Lucifer had stepped aside, as he was more hated than Castiel – but just barely. And the knowledge that their Dad could have put Heaven right if he just cared enough …. Cas couldn't allow himself to follow that train of thought any further, because it only made him angry. It was enough to almost make him understand why Lucifer rebelled against him. Almost.

Cas wanted to be part of the fight, but also he didn't. He was afraid for Sam and Dean, and he was a little afraid for God, even though he didn't know if it was enough to triumph over his anger. Still, it was better to leave it all to Lucifer, as he was the Archangel, and could do more than Cas could even think of.

So what had gone wrong? With time, maybe Cas could sift through what he had of Lucifer's memory and figure it out. All he knew was he had one horrible minute of awareness, where he felt some pain in his vessel and an even worse pain that seemed to tear across his brain like a lightning bolt. Lucifer screamed inside his mind, and it felt like his neurons were being torn apart at the roots. For a few seconds, Cas was horribly aware. He was alone in his vessel again, no longer tormented, and he thought he heard Dean shout his name, but then there was nothing. It was weird; it was also wrong.

Maybe this was what humans called shock. He felt weirdly adrift inside his own body. Had the Darkness damaged him in some other way? He wasn't sure. Cas felt himself drawn back towards consciousness by need. Actually, by Dean.

Dean didn't – or simply didn't want to - know the depth of their connection. There were some intangibles to it, something that wasn't telepathy – normal humans didn't have that ability – but it was close. If Dean was really in trouble, if he was dying, Cas could feel it. When Metatron killed him, it was like this background hum, that Cas was barely aware of, suddenly stopped. All was silence, and darkness; void filled the connection. It was awful. Had Dean been aware of the same thing happening when Cas's grace was ripped out, or were humans simply not attuned to energy enough to sense that? Having been human for a while, he understood that humans were a bit limited with their sensory ranges.

Every now and again, Cas would pick up a solid feeling of terror from Dean, something monstrous and terrible, only to walk in on one of Dean's nightmares. In the early days of dreamwalking, to see what was on Dean's mind, he didn't bother him by revealing himself. He still kept to that, although if the nightmare was so awful, he'd nudge Dean towards consciousness. That way, Dean could keep his fears to himself, and Cas allowed him that privacy, or at least the illusion of it. Because if you knew Dean at all, you knew what terrified him the most.

Dean's desperation was getting through to Cas, even in his … what did he call it? Fugue state? It was like Lucifer being smited had reverberations through his vessel, through his grace. It was like he was dizzy in his own head, and he couldn't quite stop it. He had to fight his way to consciousness, and he could feel it slipping through his hands all the while. He hoped this was temporary, the effect of being ground zero of an Archangel smiting.

To Cas, it felt like he was prying his own eyelids open from the inside. The light in the … where were they? Was this a warehouse, a factory? He wasn't sure Lucifer even let him in on that. It was industrial and mostly empty. He was slumped against a pillar, tasting blood in his mouth, and there was a body on the floor several feet away from him. Was that Chuck? It must have been, because the big, blurry shape of Sam – pretty unmistakable – was beside it. Checking for a pulse? Cas didn't know. He didn't know if God could even die, although … why not? Everything eventually died. Even angels, even the universe. The void was here before everything, and it would be here after. Nature abhorred a vacuum, but the universe itself did not.

"Cas?" Only now did he realize this wasn't the first time Dean had said it. He was beside him, on his knees. He had a little blood at the corner of his mouth, but otherwise looked okay, as long as you ignored the pain in his eyes. Dean was hurt, but, as usual, was trying to pretend he wasn't. Dean was a very big proponent of the "fake it 'til you make it" philosophy, having lived most of his life that way. It was unusual in the fact that it was heartening and disheartening in equal amounts.

Seeing his eyes open, Dean took his face in his hands, and Cas realized that was the first touch he'd felt since Lucifer in the cage. Dean's face, even this close, was still blurry, and slightly doubled. Cas really didn't feel well at all. Maybe this was how Dean felt after the angel smiting. "Cas? Buddy, you still with us?"

"I am," he said, trying to focus. Maybe if he could focus on one specific point, his head would stop swimming. Right now, reality seemed to be pitching and yawing like a boat on a storm tossed sea.

Cas had chosen to focus on Dean, since he was the closest object, and the relief that flooded his expression was amazing. He closed his eyes, and tightened his hands on his shoulders. "Thank G-" he stopped himself awkwardly, refraining from saying God, and that was for the best. Cas was sure God had nothing to do with this.

"Is she gone?" Cas asked, because he honestly wasn't sure.

Dean opened his eyes, and his expression pretty much said it all. He looked bereft. "For now. But the fight's not over. I mean … maybe it is, I dunno."

From shredded scraps of Lucifer's memories, and his connection with Dean, Cas could almost put together what happened. The crappy plan not only failed, but backfired. The Darkness had won this battle, and possibly everything. The void might be filling things sooner than any of them anticipated. Dean stared at him, and Cas knew he was trying not to despair, and was failing miserably. It was kind of sweet how Dean thought he was successfully promoting being an unfeeling macho man, when anybody who knew him for more than five minutes knew he was, to quote Lucifer, filled with marshmallow fluff. Dean didn't want to care, but he probably cared a little too much for his own good. Cas figured they had that much in common. "Time for plan B," Cas said. It looked like the ceiling was spinning. It wasn't, was it?

Dean scoffed. "Yeah. And if we had one that would be great." He looked away briefly as tears started to well in his eyes. "I think we're really fucked this time. Just promise me you're gonna stay with me, okay? I need you."

Especially if it was the end of all things? It occurred to Cas that if things were ending, he wanted to be with Dean and Sam. It only seemed right, didn't it? Almost poetic. "I doubt I'd be much help."

"You're wrong. It hasn't been the same without you." Dean attempted to smile, but it was so pained and so forced it instantly collapsed. "I'm sorry. If I did something to –"

"Dean," he interrupted, not too forcefully. It wasn't that he didn't want to hear Dean apologize, because he totally did, he simply wanted to be fully conscious for it. He was losing the battle in his head, and was fighting to keep his eyes open. "Give me a minute. Then we can work on plan B."

If it was indeed the end of everything, at least they could all go out fighting. That was the Winchester way, right?

The End (For now ..?)