When Sam was hallucinating Lucifer, Lucifer tried to make him commit suicide. Now Castiel is hallucinating Lucifer and Lucifer is trying to talk him into killing Sam.

"You," said Lucifer, somewhere around day three, "should kill Sam Winchester."

It came in the middle of a long and intricate ramble about the various ways in which humans were overall useless and disgusting, and thoroughly jarred Castiel out of his hard-won trance of ignoring every word from the manifestation's mouth. Castiel was not entirely certain what Lucifer was, but it was enough to know that his company was not terribly pleasurable.

"Why?" was the first question out of Castiel's mouth, unfortunately. Lucifer cast him a look that was very nearly scathing.

"Why? I should think it obvious."

Castiel narrowed his eyes. "Not to me."

Lucifer's smile was thoroughly patronizing. "I might have known. You never were the brightest, little brother. Let me put it this way." He leaned forward slightly. "Is Sam any better, really, than he was before you pulled this little switch?"

Castiel hesitated before voicing his, "No. Not really. His soul is…still damaged."

"So all you have done is delay the inevitable." Lucifer folded his hands over his knees. "Do you think Sam's next descent will be any less painful?"

Castiel twisted his hands together and picked at the skin, a nervous habit he'd learned as a human and apparently hadn't lost. "N-no."

"And don't you want," Lucifer said soothingly, "To spare your friend any unnecessary pain?" He reached out and touched Castiel's cheek, gently, gently. "Come now, Castiel. You know it's only for the best."

The demon that called itself Meg was his only visitor. He looked up when she slipped in through the door and asked, quietly, "Any word?"

"On the plaid monstrosities? No. From them? Also no." She smirked at him, voice taking on a mocking edge. "Don't seem too inclined to call on you, do they?" He could see the abomination writhing under the surface of her skin. So easy to reach out and burn it to oblivion-

"They are otherwise occupied," he said dully. "I do not expect contact."

"You just want to know if they're dead yet." The demon pulled her host's face into a pout. "What, fly-boy, I'm not enough for you?"

The noise Lucifer made was eloquently disgusted. "Kill her," he suggested, "Snuff her out and leave this place. Find the Winchesters. Kill Sam. Simple." Castiel twitched. "Coward," Lucifer launched at the back of his head. "You never could do what needed to be done. I am almost embarrassed to be your elder brother."

"You're in luck," Meg was saying. "Or they are. Or maybe both. Doesn't look like they're quite dead yet."

Castiel lifted his head. "So you have heard."

Meg snorted. "No," she said. "I'm just pretty sure based on the fact that I don't have demons coming out of my ass. Crowley would never admit it, but the Winchesters make him a little nervous. It's the crazy, you understand. Makes them unpredictable. Crowley doesn't like unpredictable."

Castiel smiled, though the expression felt ghostly and didn't quite fit right on his face. "Good."

The demon titled its head at him. "Seem more lucid today."

"Lucid is as lucid does," Lucifer said, and Castiel flinched.

"All your pretty words about mercy," Lucifer said, pacing back and forth in a perfectly straight line in front of the windows, his shadow falling almost to Castiel's feet as he crossed the light. "What was it you said? If you wanted your brother dead, you should have killed him outright. And here you are, the one sucking them slowly dry."

Castiel thought of Sam's empty eyes looking up at him blankly, without recognition. You're not real. He thought of the hollow look in Dean's eyes and the smell of whiskey on his skin. "It would be a mercy to kill Sam," Lucifer murmured, pausing and turning to level calm pale eyes on him. "For both of them. Don't you think you owe them that, after everyhing you've done?"

"What I owe," Castiel said, closing his eyes briefly, "Is for them to decide. Not for me."

"If you won't think of Sam, perhaps Dean," Lucifer went on casually, picking apart the sandwich that Castiel was ignoring. "Poor Dean. Doesn't know how to fix his brother, how to save him. Like dragging a weight around he doesn't know what to do with but can't get rid of. You could help."

"Dean would not thank me for the help you suggest," Castiel said tightly, remembering the look on Dean's face, the desolation when he told his friend there was nothing he could do for Sam.

"You know I can take care of him better than anyone else. I love Sam as no one ever has," Lucifer said, and then smiled, a toothy, sharp, nasty thing. "I promise I won't break my toys this time."

Castiel dug his blunt fingers into his own palm. It didn't hurt, but it was something. "No," he said.

"Give me one good reason why not."

"I don't want to."

"I'm sorry," Lucifer said, dropping the sandwich and coming over to lay a cool hand on the back of Castiel's neck. "That's not a good reason."

"Just think about it," Lucifer said casually from where he was perched on the table. He'd barely been quiet for an hour this time. "Let it percolate a while. You're a pretty smart kid. And it's the only thing that really makes sense. You know it. I know it. I'm pretty sure even Dean knows it, he just doesn't have the guts to admit it. I used to try to tell Sam, but, well…" Lucifer shrugged ruefully. "He wouldn't stop telling me what it would do to Dean."

"It would break him," Castiel mumbled quietly. Lucifer laughed, raucous and loud.

"Break him? Did you see that boy, little brother? He's already broken. Has been for a long time. Maybe since you went off the rails, you think?" Lucifer leaned back on his hands. "What do you think it was that pushed him over ? His brother going nuts or his only friend betraying him?"

"You are the Prince of Lies," Castiel said, picking at the sheets on the bed. "I will not listen-"

Lucifer tsked. "Oh, come," he said. "Just tell me, Castiel. Does it really sound to you like I'm telling lies?"

Castiel swallowed hard and looked away. The door opened and the demon calling itself Meg stepped inside with a cheerful, "Meds, Emmanuel!" She waited until the door closed behind her to add, "So, what is it today, half sane or mostly crazy?"

"Mmm," said Lucifer from the table. "Disgusting creature. I was mistaken to create them. And not all that useful in the end, either."

He didn't leave with the intention to follow Lucifer's suggestion. He didn't. The walls were closing in tightly, the air felt charged like something dark was coming, and he could stand and walk and function. It was good enough. Perhaps he could be of some use, instead of being locked away like an artifact too valuable to use. Or too dangerous.

More likely, some bitter piece of him thought, the latter.

When he left, he thought only of going to see the Winchesters. To ensure that they were well. When he landed in their motel room to find them both asleep, however, he stayed. Dean slept like the dead and he reeked of alcohol. Sam…

Sam was curled up in a fetal position with the blankets thrown off, twitching violently and soundlessly. "Aww," said Lucifer. "He's still dreaming about me." He leaned down and rested his chin on Castiel's shoulder. "What do you think it is this time, the messy physical or the messier psychological?"

Castiel half took a step forward, thinking to reach out and calm Sam's dreams, perhaps, but Lucifer held him back. "You're treating a symptom," he said. "Nothing more. Hardly even that. Here's a thought, little brother: you keep him alive. Keep him going, staggering along a little at a time. How long do you think it'll last?" Lucifer lowered his voice. "Suicides don't go to heaven, Castiel."

Castiel felt a chill travel down his spine. That won't happen, he thought, and Lucifer snorted.

"You don't think so? I know him better than you do, and I respectfully disagree." Lucifer stepped away and wandered over to look down at Dean. "Kill Sam now and maybe he has a chance of making it to Heaven. Wait, and in the end it's likely he'll only damn himself." Lucifer smiled in Castiel's direction, teeth gleaming white. "It's what he does, isn't it?"

Castiel swallowed hard and squeezed his eyes closed. I won't let that happen.

"There's one way to stop it," Lucifer said softly, turning to face Castiel. "One simple way."

On the bed, Sam shuddered and curled up more tightly. Castiel could see his fingers digging into his chest. Lucifer crossed to stand beside him and rest a possessive hand briefly on his brow. "Kill Sam Winchester." Lucifer leaned down and pressed a light kiss to Sam's hair. "Let him rest."

Sam clawed his way out of yet another nightmare to find Castiel watching him with unnerving intensity, right at the foot of his bed. "Huh?" he said, before fully registering that it was Cas, here, and sitting up the rest of the way. "Jesus, Cas! You're-"

"Sam," said Castiel, and there was something in his eyes for a moment that made the hairs on the back of Sam's neck want to stand up. The angel took a step forward, and Sam fought the urge to shrink back.

A rustle to his left and they both looked over to Dean's stirring. "S'm," Dean said into his pillow, "Who the fuck are you- wait, is that Cas?"

"Is something wrong? Are you okay? Jesus, how long have you – you could have woken us up." Sam said, quickly, while Dean was still catching up. Castiel seemed to hesitate a moment, and Sam thought his gaze shifted left, but then he nodded slowly.

"I am well. Nothing is amiss. As I am in command of myself again, I thought…"

Dean rubbed his eyes. "Give a little warning next time, Jesus," he said, and then narrowed his eyes in Castiel's general direction. "You're…all right? Seriously? Cause when we last saw you you looked a little…"

(Sam tried not to feel a twinge of guilt in his gut. Castiel had taken his insanity. His suffering. Or at least the worst of it, though the rest was still there, lurking around the edges.)

"I am not human," Castiel said, stony-faced. "I am rather more equipped to…cope. It was merely a shock." Sam felt a shiver crawl down his spine and a moment later could not have said why. "I wish to be useful."

"Honestly," Dean said, looking like he had a headache and more than a little irritated, "You'd probably be more helpful-"

Sam cut him off. "Yeah," he said. "Yeah, makes sense, that'd be…that'd be good. We can kind of use all hands on this one, I think." He ignored Dean's glowering at him. "Thanks for coming."

"You are welcome." Castiel's gaze flicked to Dean briefly, and then fixed back on Sam.

"Are you gonna share a bed with Sam or something? Cause otherwise…"

"Oh," said Castiel, "Yes. Of course." And he vanished. Sam blinked.

"He seem weird to you?" he asked, cautiously, and Dean flopped back and threw an arm over his eyes.

"Dude, seriously? He's Cas. He always seems weird to me."

"Sam."

Sam almost jumped out of his seat, and, worse, nearly pulled a gun as Castiel appeared next to him in the records office. "God," Sam said, sinking back down. "I almost shot you."

"It would not affect me."

"Yeah, but it might affect my ability to research here." Sam ran a hand through his hair and frowned at Castiel. "What's up? You kind of…vanished."

"I have been." Castiel paused, and seemed to be looking somewhere into the distance, between the shelves. "…seeking answers."

Sam blinked. And wondered, briefly, when Castiel had gotten more inclined to lie. And why. "Cas," he said, slowly. "Are you sure you're actually…you know. Okay? Cause I know-"

"Yes," said Castiel, before Sam could even finish formulating his thought the rest of the way. "I am fine. Do not worry for me." Castiel shifted, briefly, from foot to foot, and glanced down the hallway. "Is there any way I might assist you?"

"Think I'm probably okay." Sam eyed Castiel carefully a moment, and then said, as delicately as he could manage, "Did Dean say something? To you? Cause he's just-"

"No," said Castiel, and did the awkward shifting thing again. "No, he did not. I have not actually spoken to him. I do not think he knows I am here."

Sam frowned, and then closed the book he was paging through, holding his place with a finger. "Look, Cas…he's still mad, but it's okay, he still…you're still his friend, you know? And he'd probably like to. Um. Talk to you."

Castiel twitched. His eyes clicked back to Sam, though they fixed somewhat over his head. He turned away, sharply, a moment later. "Sam," he said, and then stopped. "—I'm sorry."

Sam tried for a smile, though his instincts were prickling wrong wrong wrong but it was just – leftover. This was just Cas. "I already told you that I don't-"

Sam's phone rang. Sam sighed. "Hold on a second," he said, reaching to pick it up, but when he glanced back up with his phone in his hand, Castiel was gone.

"I think Cas is still a little bit…off," Sam said, carefully, to Dean. Dean glanced sideways at him, eyes slightly narrowed.

"By which I guess you mean crazy."

"Yeah," said Sam after a moment's pause. "I guess."

"You really surprised? The guy's got to be a mess." Dean shrugged one shoulder. "This point we all are." Sam rubbed the bridge of his nose vigorously and tried to work out how to put this.

"Yeah, I know, but – there's just something. It's kind of creeping me out."

Dean stopped and set down the flask he was absently playing with, turning to face Sam. "Okay. Sam, if you…if you don't want Cas aroud, I get it. I don't know that I do. But you can just say-"

"That's not it," Sam interrupted, feeling a burst of hot frustration somewhere under his sternum. "It's just…dammit. Never mind. It's probably nothing." Dean's eyes narrowed.

"Don't pull that shit on me."

"I'm not," Sam said, tightly. "Pulling anything. It probably is nothing. Just…you know. I'm still a little twitchy, that's probably all it is." Not his most convincing performance, perhaps, but what did he have, really? If Castiel didn't want to accept help, he wouldn't. It was that simple. Nothing he could really do about that.

The next time the angel cornered him alone it was in the motel room, when he appeared way too into Sam's space while Dean was making a coffee run, almost looming even from his shorter height. Castiel's eyes were boring into him with unnerving intensity. "Hello, Sam," he said.

"You know," said Sam, managing not to jump by sheer force of will, "It wouldn't kill you to knock."

Castiel didn't answer. Appeared to be eying him, the corners of his mouth turned down in the slightest of frowns.

"Look, Cas," Sam said finally with a sigh, "If there's something you want to say to me, can you just go ahead and say it?"

Castiel nodded, slowly. "There is something I know I must do," Castiel said, "But I very much wish not to for what I fear are selfish reasons."

Okay, that didn't sound good. Sam narrowed his eyes. "What is it you have to do?"

"Sam," Castiel said, and then sighed. He shook his head, and his eyes went left of Sam's head again, seeming to be listening. "Yes," he said, after a moment. "Yes, of course," and the prickling down Sam's spine had grown into full-fledged shrieking in his head.

"Cas," Sam said, "What-"

The angel crowded closer and appeared to be gathering himself. His eyes met Sam's, and there was something empty, blank, and terrible about them. "I cannot guarantee I will make this painless," he said, "But I will endeavor to make it quick." He raised his right hand and stretched it out, and Sam could feel the power crackle in the air.

Oh god snap out of it any time now this isn't real this isn't-

He was going to be torn up and stripped bare and emptied into the wind and-

"Hey, I'm – Jesus fucking Christ!"

(Dean. Dean Dean Dean.)

He didn't register the angel's departure. Just Dean, suddenly at his side, and the sting from where he'd tried to dig through the wall behind him. "Sam," Dean was saying, an edge near to desperation in his voice. "Sam, Sammy, are you okay? What the hell just-"

"Hey Dean," Sam said, and tried for a smile. "I think Cas's lost it."

Dean was pacing back and forth. Sam watched him and picked idly at the bandaids over his shredded fingertips. "What the hell," he was saying. "What the motherfucking hell. Cas was trying to- what?"

Sam felt the urge to laugh and choked it down. "Kill me," he said, "Pretty sure."

Dean wheeled, glaring at Sam like it was his fault. Which it was, a little. Probably. "Why the fuck would he-"

"I don't know." Sam forced his hands apart and clenched them into fists instead. "Sounded like a good idea? I just know-"

"Jesus," Dean said again. "Jesus." Sam's heart still felt like it was thudding too hard. "Cause that's what we needed, more people out to kill us-"

"Pretty sure just me," Sam said. "Considering he keeps only turning up when I'm alone." Dean shot him a look that was uncommonly dirty.

"This isn't fucking funny."

"No," Sam agreed. He could feel something like hysteria tickling at the back of his brain, and pushed it away. "It really isn't. Our angelic best friend wants to kill me. But he's sorry about it, so you know, that's okay."

For a second, Sam thought Dean was going to hit him. He didn't, just swore and turned sharply away. "Maybe we can snap him out of it somehow. Maybe there's something we can-"

There was something like cold inevitability settling on Sam's shoulders. It didn't seem worth ignoring. He clasped his hands together and said, "You know it's probably because of…because he took the worst of the crazy. From me."

"How does that-"

"I could always take it back."

Dean wheeled. His eyes were like flint. "Shut up," he said, flatly. "And never suggest that again."

Sam felt a private little (awful) flood of relief. There was some small (maybe not so small) part of him that had feared that Dean would pause and then say yes, that's it, exactly, need him more than you anyway.

Sam hadn't claimed not to have issues for a long time now. He just wasn't sure whether to feel guiltier for thinking it or guiltier that he was relieved.

It'd been a while since Sam had seen Dean jumpy.

Sure, he was masking it now with irritability and constant motion and snappishness, but Sam knew jumpy when he saw it, and Dean was. Sam couldn't really blame him. After all, there was an angel somewhere around with a yen to put Sam out of the picture permanently. Dean had never really taken well to that one. Even when it would make things easier.

(Like, it occurred to Sam somewhat grimly, right now.)

He couldn't quite find it in himself to wish that Dean would change his mind, though. Not with the hospital so close behind him. He'd been so tired then it was easy to resign himself to death, but now he could only remember how it felt and feel a sort of sick clenching in his gut, certainty that he did not want to feel that again.

Castiel hadn't come around again since Dean had caught him in the act. (Like sex, the semi hysterical part of Sam's brain piped up. Hahahaha.) He was somewhere out there, undoubtedly. Planning his next move, maybe. That was what had Dean jumpy.

What had him sticking to Sam like a burr. "You said it yourself," Dean almost snarled. "He only turned up when you were by yourself. Obvious solution."

Sam privately did not think that it would be terribly effective, and that Castiel would find a way around Dean eventually unless they came up with something more permanent, but telling Dean that would be worse than useless.

So he went along with it. Hunted angel wards and hoped they were accurate. Looked up ways of banishing angels other than the ones they already knew. Every so often, thought about researching ways of killing them. (He never actually did, though. Couldn't quite…when he thought about it, he felt a little sick. It wasn't Castiel's fault.)

(He might not even be wrong.)

Castiel still caught up to them, though. Even for all that. All it took was a couple seconds, Sam taking bags to the house they were squatting in this week and Dean checking the perimeter, and Castiel was waiting in the empty kitchen. The angel looked ragged, exhausted. A little wild around the eyes.

Sam froze.

"Cas," he said. "Hey." His feet felt rooted to the floor.

"Sam," said Castiel, and his voice was pleading. "Please just let me – I can help you." The angel took a step closer. "It's for the best."

Fear was leaving him numb. Sam stayed where he was. "Cas," he said, carefully. "We want to help you. You're not okay, you're not thinking straight-"

"Sam!" Someone was yelling, and he heard a thud. Front door closed, probably locked. Dean outside. End of the line Sam here's looking at you- "Sam! –Cas if you touch him I swear to god, I swear-"

"Dean will understand," Castiel said, his gaze painfully earnest. "Please. It is the only thing I can do." Sam realized that he'd backed up against the table and couldn't go any farther and glanced over his shoulder. When he looked back Castiel seemed a great deal nearer than he had been. Barely an arm's length. "Allow me my absolution."

"Don't touch me," Sam said, more weakly. He heard the splintering of wood somewhere through the roaring in his ears as his vision narrowed to Castiel's hand reaching out to him, resting against his chest, over his heart, and-

-stretched thin pulled out and dismembered to the very core, flayed open and spilled into the dark-

"Hey!" Not dead yet then. Not yet-Dean. When had Dean gotten there? When had-

Dean slammed a bloody hand into the sigil and Castiel burned away in a blaze of light. Sam was left blinking with the afterimage, his heart pounding like it was about to explode, sagging against the table as his knees went weak. "Sam," said Dean, voice hoarse.

"I'm okay," Sam said, though he wasn't quite sure. "I'm…I'm okay." He squeezed his eyes closed.

"Too close," Dean said, roughly. "That was too fucking – twenty goddamn seconds." Sam opened his eyes.

"We just going to keep doing this forever?" he asked, looking at Dean's tight jaw and slightly trembling hands, the exhaustion writ large under his eyes. "Fighting Leviathans and Cas and the whole damn world?" It's just me.

"Shut up, Sam," Dean said, smearing the blood from his palm off on his pants. "That's what we do, isn't it? Keep fighting. Keep on fucking fighting no matter how stacked the deck is. We're just that dumb."

Sam snorted, grimly. "Yeah," he said lowly. "I guess we are."

Castiel reassembled the fragments of his being somewhere in a desert and still felt like he was coming apart at the seams. He held perfectly still under the beating hammer of the sun.

Lucifer ran a hand softly through his hair. "He wouldn't be Dean if he didn't fight against the inevitable," he said, soothingly. "You're doing the right thing, Castiel." His older brother leaned in and kissed his temple, lightly.

The air was hot and dry and almost seemed to burn the inside of his vessel's nostrils. There was still time. Do not doubt. You cannot doubt.

"Don't worry about your failure," Lucifer purred, breath cool on borrowed skin. "We'll get another chance. Sooner or later, little brother. Sooner or later."