On the last day before the end of the world, Castiel slept.

"Hello, brother."

It was amazing, Castiel thought dimly, that he could hear the difference just in those two words. In tone, inflection, in the way that voice that he'd heard so little and so much was suddenly a weapon. It made him ache and burn with a fierce kind of anger he'd forgotten he possessed.

"I am no brother of yours."

"Hardly, anymore." Lucifer smiled, Sam Winchester's mouth curved into a smile as cruel as it was kind. "I couldn't do this, otherwise. That's the payment given for turning your back on their plan, Castiel. Do you like it?"

"You're playing to the same plan," Castiel accused. Lucifer smiled at him, though it faded in a moment and he slid his hands into the pockets of Sam's jacket and looked at the bar around them.

"Interesting choice of location."

"Do you have to do this?" Castiel asked, feeling himself nearly vibrate with something between anger and grief. It was over now. All they had to do was wait.

"Do what?"

"Gloat." Castiel hunched his shoulders. "You won. You have what you wanted. Your vessel. And you'll get your fight."

Lucifer tilted his (Sam's) head, looking curious. Then comprehension dawned on his borrowed features, and he almost seemed amused. "It's not just the end of the world, is it, Castiel? This is personal for you. You like Sam. That's…surprising."

"Why?" Castiel demanded. Lucifer laughed.

"You need to ask? You were assigned to Dean Winchester for a reason, Castiel. Obedient, loyal, a warrior and not a thinker. You're alike."

"I fell for Dean Winchester," Castiel snapped, and Lucifer waved a hand.

"And Dean Winchester fell because of Sam," he said, almost carelessly.

Castiel clenched his fists. "It doesn't matter," Lucifer said casually. "I'm touched. I'll pass your affection on to Sam." He lifted a hand, examined his stolen fingers. "We're still getting used to each other, but you should know that he's safer than he's ever been, with me."

"Sam isn't you," Castiel said, impassioned, and Lucifer raised one eyebrow.

"No?"

"No," he hissed. "Sam is loyal to his brother. Sam is compassionate and thoughtful. Sam didn't want this."

~.~

Sam found him a little after midnight.

Castiel did not move from his perch on the porch, let Sam hover awkwardly in the doorway. He was tired, but unwilling to surrender to it. If he slept, he might miss the last few shreds of grace leaking away.

He heard Sam shift and clear his throat. "…you okay?" the younger Winchester said at last. Castiel shrugged.

"I believe 'I'm fine' is the customary answer?"

Sam made a soft huffing sound that was probably supposed to be amusement. "Yeah," he said, "I guess it is. Mind if I – sit down?"

Castiel merely shifted to the side in answer, and Sam sat down with a sigh a moment later. The once angel didn't need preternatural senses to feel the tension in the other man. "It is late," he said, after long moments of silence. "Shouldn't you be asleep?"

"Yeah," said Sam, and grimaced. Castiel narrowed his eyes.

"Lucifer?"

"Y-look, it doesn't matter. It's just-" Sam stood abruptly, ground a hand into his eyes. "I had a thought. An – idea. Wanted to run it by you."

"It won't work," said Castiel flatly. Sam shot him a look and Castiel grimaced. "Fine. What is it?"

Sam cleared his throat again, looked away for a moment. Then he met the former angel's eyes and said, "I say yes, you open the gate, I – jump. Drag Lucifer down with me."

Castiel's mind went completely, utterly blank. Sam hurried on.

"I mean – we have a trap, right? But he's never going to just walk into it-"

Castiel got his voice back and just remembered to keep it low as he hissed, "Are you out of your mind?" Sam flinched, very slightly.

"Cas," he said, "I can-"

"No," Castiel said. "No. That's the stupidest-"

"Then how are we going to do this?" This time Castiel heard the panic squeezing Sam's voice. "It makes sense, even if I can't win – I can at least distract him, slow him down-"

Castiel lurched to his feet and grabbed for Sam's shirt. "You don't know," he said, "What you're agreeing to."

A momentary flash of anger lit Sam's eyes. "Cas-"

"No. Let me tell you," Castiel said. "Let me – let me tell you how it would be. If you failed – everything else aside, you would be locked, screaming in your own mind for eternity. And if it worked – you would be in Hell. Worse, in the Cage itself, alone with Lucifer, and there would be no getting out, no mercy, no respite-"

"You think I can let that matter?" Sam's face twisted in what looked like anguish. "I have to do something!"

"But does that have to mean throwing your life away?"

Sam's jaw tightened. "Do you think I'm that selfish?"

"No," Castiel said, lowering his voice, "I am."

Silence ensued. Sam stared at him, incredulous. He saw Sam swallow. "Cas?" he said quietly.

The former angel straightened deliberately. "You wanted to know my opinion. You have it. Don't waste your life on a slim chance."

"And if it's our only chance?" Sam asked, voice diminishing.

"We'll find another way," Castiel said firmly. Sam sighed.

"Cas…"

"We'll find another way."

Sam's eyes dropped, and he nodded, barely. "Okay," he said. "Okay. I – got it."

"Do you?" Castiel asked, and Sam looked up at him.

"No," Sam said finally. "But I'll go along with it. Long as things don't get worse."

~.~

"Sam has been mine since the day he was born," Lucifer said, with the faintest of frowns, like the one Sam got when he was slightly puzzled by something, or faintly displeased, like when Dean left his underwear on the floor or didn't wash his shaving cream down the sink. "His family turned on him. As mine did on me."

"You rebelled."

"Didn't you?" Lucifer cracked Sam's neck. "Besides, Castiel. You talk like you've been such a friend to Sam yourself. You…how instrumental were you in leading Sam by the nose all the way to opening my door – though I have to thank you for that – and how instrumental in casting him out for it? What role did you play in dividing Sam from his brother? What role in sowing mistrust? Ah yes, you – a true friend."

Castiel almost wanted to cringe. Lucifer's eyes in Sam's face were cold and calm and implacable. "He called me his friend," he protested.

"Sam is quick to forgive," Lucifer said, with a small smile. Almost affectionate. "I am not."

"If you mean to kill me-"

"You're so unimaginative." Lucifer didn't sound angry, just scolding, as though Castiel's lack of imagination was a minor annoyance to be acknowledged and then ignored. "I won't kill you, Castiel. I don't want to. You're a unique creature. A fallen angel who still believes."

"What, then?"

"You'll live," Lucifer said, and smiled. "You'll live to see the world I make, and to know that it's a better one. And you'll bow, and you'll beg forgiveness of me for what you have done."

"No."

"There's nothing you can do, Castiel," Lucifer said, his voice dropping again, becoming soft, compassionate. It almost sounded like Sam, could have almost sounded like Sam, if Castiel didn't listen so closely. "It's over."

"Why come to me, then?"

"I like you." Lucifer locked his hands behind his back and looked evenly at Castiel. "You're different. Special, if you will. I could give you back everything you lost, in time." He looked directly at Castiel. "And Sam wanted to see you. He asked for Dean as well, but…well, I thought that unwise."

Castiel's insides squirmed. "Is he listening?"

"Of course." Lucifer's eyes were distant for a moment. "To every word. He wants to apologize." He half closed his eyes. "Tell him he doesn't need to apologize, Castiel."

"You don't need to apologize, Sam," Castiel said, almost choking on it, and hated himself a little for not quite believing it. You never should have done this. We should have continued as best as we could. Found another way. Some other way. "Please," he said, then. "I'd like to…speak with him."

"Why?" Lucifer seemed almost entertained by the request. He tilted his head again, as though listening, and then quirked a smile. "Now, Sam. That's enough."

"There's nothing I can do," Castiel said. "You said it yourself."

Lucifer seemed to think for a while. "That's true," he said, and paused a moment longer. "Very well," he said at last. "A few minutes. Then we must be going. So much to do, you know."

~.~

"I used to have so much faith," Sam said abruptly, looking at the ceiling and playing with the blanket between his fingers. "I don't even know what happened."

"I can guess," Castiel said sardonically. Sam glanced at him, and half smiled, a strange and slightly bitter expression.

"You're not so bad. The first time I saw you…"

Castiel shifted from one foot to the other and back again. "I…remember." He remembered the stern, judging gaze he'd leveled on Sam, the refusal to even touch his hand, practically smelling the demon blood. It made something in him twist uncomfortably now. Sam didn't seem to be thinking the same thing, judging by the way he smiled.

If a little sadly.

"Seems like a while ago now, doesn't it."

"Do you still believe?" Castiel asked abruptly, and Sam looked at him like Castiel might be, perhaps, a little off his head.

"…in what?" Sam seemed amused, again, and Castiel was almost frustrated by it. "I mean, I went to heaven. And I'm sitting next to an angel. Under the circumstances, belief seems a little…I don't know, moot?"

Castiel frowned. "A poor way to put it, then. Do you still have faith?"

He wasn't amused anymore. "In what?" he asked, but softer, this time. Castiel shrugged one shoulder, and Sam looked away.

"I guess," he said, slowly. "I do, yeah, in a way. Not in the same way. But I still…" he trailed off, shook his head. "This seems a little weird, sorry," he said apologetically. "Talking about this to you, of all people."

"It's not something I've thought about," Castiel said honestly. "Before, it just…was. An angel is faith."

"And now?"

Castiel shrugged. "I don't know what I am."

"Yeah," Sam said after a moment. "I hear that."

"You're still human," Castiel said, firmly. "Whatever…you're still human." Sam smiled like he didn't quite believe it. Castiel supposed he couldn't hold that against him. "There are things I believe in," Castiel said, finally, suddenly.

"Yeah? What's that?" Sam sounded genuinely curious.

"I believe in Dean," Castiel said honestly, feeling a little foolish as he did, and he should have known better than to expect Sam to laugh. He just nodded.

"Yeah," Sam said softly. "I always have. Even when there was nothing else, you know?"

Castiel thought of Dean insisting he would say yes to Michael. Of Sam insisting that he wouldn't. That kind of faith could move mountains. Change fates. Castiel thought of Sam falling into Hell and met the younger Winchester's eyes.

"I believe in you, too," he said, and for a moment Sam was just quiet. Then he cleared his throat.

"Yeah," he said, low and rough. "You too, Cas."

~.~

He saw the moment when it was no longer Lucifer but Sam, and wanted to move but wasn't sure where to. Sam blinked, seeming momentarily surprised, and then focused on Castiel. He looked strange, wide-eyed and confused.

"Cas," he said, "Oh Jesus. Cas. I-"

He grabbed the bar top. It was melting, Castiel noticed, and under Sam's hand was a spreading pool of – something. He didn't want to think about what. "It's okay," Castiel said, even though it wasn't; it was the kind of thing he thought one was supposed to say in these cases. "Sam-"

"I'm sorry," Sam was saying, "I'm sorry, Cas, I tried, I couldn't-"

It hurt, Castiel thought, that this was going to be the last he saw of his friend. That this would be the last image he had of Sam Winchester, scared and half-broken and still fighting even while the world burned down.

"Sam," he said, as firmly as he could. "It's all right."

"Tell me you've worked something out," Sam said, and then shook his head. "No, don't, he'll-"

There was nothing he wanted to say less, but even if Castiel wasn't Dean, he knew a few things about when to lie. "Trust me," he said, because he couldn't be more specific than that, and already he knew that his lies were a failure. Sam seemed to calm anyway, and stare at Castiel with something terrifyingly like hope. "We'll find a way," he said.

"Please," Sam whispered, and Castiel didn't know what to do, but he knew it had to be something.

And then it was Lucifer again, with his soft smile and hard eyes. "Good night, Castiel," he said and reached out, leaned down and kissed his forehead with a terrible kind of tenderness.

~.~

On the last day before the end of the world, Sam and Castiel were sitting out on the porch watching the moon set. "You know," Sam said, "I was never baptized. Is that important?"

"Important to what?" Castiel asked. He thought he might have been a little tipsy, but he couldn't tell.

"Oh, I don't know." Sam seemed awkward. "If I weren't going to Hell – provided things actually go right tomorrow – would it help? You know, cleanse my immortal soul or whatever."

"I have never heard that it made any particular difference."

"I always liked the idea," Sam said, after a moment's silence. "Not sure why." He paused, fingers tapping out a beat to some song that Dean would have been able to name on the step beside him. Castiel glanced at the man beside him and thought about the day to come.

"If you would like to be baptized," he said, suddenly, and Sam looked at him like he had that first day. It almost embarrassed him.

"Would you?"

"Of course." It would be more, Castiel thought dully, like anointing the body for burial, but he didn't say that. It made his chest hurt. Sam wanted this. Sam, who Castiel sometimes thought he was just beginning to know.

He'd promised they would find another way. And hadn't. Beside all his other failures of this man, that somehow seemed the worst, just for a moment.

"It doesn't take much," Castiel said. "Just a little water."

"Would holy water be better?" The eagerness in Sam's voice made Castiel's stomach twist.

"It wouldn't be worse." Sam fetched a jar of it, crucifix sunk at the bottom, and Castiel opened it, dipped two fingers in, and cleared his throat. "You should sit down," he suggested, and Sam sat, bowed his head.

Thinking of his lost grace and all his failures, Castiel felt like a fraud as he drew the sign of the cross in water on Sam's forehead and murmured, "Ego te baptizo in nomine Patris, et Filii, et Spiritus Sancti," and watched the water vanish even as he spoke, except a single drop that ran down to the corner of Sam's eye and further, like a tear.

His heart felt heavy. Sam smiled at him.

"Hey," he said, "How many people can say they got baptized by an angel?"

"Sam," Castiel said, and wasn't sure what he was going to say.

"Thank you," said Sam, and Castiel swallowed. He wasn't sure what he wanted. Wasn't sure what to think.

"Go in peace," he said, formally, "to love and serve the Lord."

"Thank you," Sam said again, and reached out, grasped Castiel's wrist just for a second. Dean was stirring upstairs. The last day of the world was beginning. One way or another, in all too few hours it would all be over.

There were many things he could have said. "You're welcome," never made the list, but it was what came out anyway.