Sam walked out into the library, pausing when he saw Kevin sitting at the table with a book on curses open in front of him. Curled on the table beside him, Paka was laying on her side, occasionally batting at the pages as they were turned. Sam made up his mind, walking over and sliding in opposite him.

Kevin looked up, marking his page and closing the book. He slid a second glass of whisky across the table, clearly expecting his company at some point.

Sam gave a weak smile. "Thanks."

"Charlie headed off to bed about an hour ago." He looked the younger hunter over. "Something you should be doing."

"I'll make it until night." Sam dismissed. "You find anything?"

"I pinky swear to you, if I ever find anything I will come get you." Kevin said firmly.

Sam frowned, taking a sip of his drink.

"How was he when you left?" Kevin asked, his voice softening.

"Wired." He responded. "Tense. Sarcastic." He looked down. "But he gave the knife back, and he let us take him back to the cabin without a fight."

"Cas is okay?"

"Yeah. Healed right up when we broke the wards."

"Was it bad?"

Sam hesitated before his shoulders slumped. "Yeah."

Kevin looked away. "And Cas is sure he's got it under control now?"

"So he says." He sighed. "He should be calling soon to check in."

"I'm sorry you can't be there."

Sam leaned back in his seat. "Me too…" He shook his head. "What if we can't get it off?"

"We'll find a way." Kevin absently ran his hand through Paka's fur. "We already know it's a curse."

"That's not much to go on."

"It's something. Something we didn't know last week. The answer is in there."

Sam was quiet for a moment. "How are you holding up?"

"Aces."

"You tell me if there's anything I can do." Sam instructed firmly.

"Yeah." Kevin replied. "I will."

Sam reached into his pocket as soon as his phone started to ring. He pulled it out, standing and walking towards the library. "Cas."

"Sam…"

"How is he?" Sam stopped. The pause did not go unnoticed. "Cas?"

"Dean is showing early signs of withdrawal." Cas responded, keeping his voice even. "I thought you should be aware."

"He-" Sam was quiet for a moment, trying to catch up to the unexpected and blunt news. "What?"

"Aside from the fact he is not healing, he has begun to grow increasingly restless and develop a tremor." Keeping it clinical helped quell the urge to panic. For now at least. "I imagine it will progress similarly to previous times when we were between cases."

Sam took a sharp breath. "Cas, you should leave the cabin." He said firmly.

"I am staying."

"He used the blade against Cain himself. That is going to be one hell of a come down. You should be out of the way."

"I will be careful." Cas said simply.

"At least let me come back and help."

"That is not an option."

Sam closed his eyes. "Come on, man. You need back up."

"No, Sam. You focus on getting this mark off his arm so we can fix this once and for all."

"Cas-"

"I should get back."

"You call the first sign of trouble." Sam warned.

"I will." Cas ended the call before Sam could object further, setting the phone aside. He sat still for a moment, taking a slow breath before standing up. He walked back into the main cabin, stopping behind the second salt line to locate Dean. He found him sitting on the very edge of a kitchen chair, head in hands. Cas stepped down from the upper landing and walked to the counter, starting to make fresh coffee.

Dean jumped slightly when Cas turned on the tap to fill the coffee pot. He straightened up, trying to focus on watching him work.

Cas brought a mug and set it in front of Dean before taking a seat across from him.

Dean leaned forward against the table, hands absently closing around the mug but he made no move to drink it. "You should get some food with that." He mumbled.

Cas frowned as he studied him, ignoring the quiet suggestion. Dean was actively trying to fight to relax, trying to quell the shaking with little success. His gaze was distant and somewhat unfocused, and kept purposely away from the angel.

Dean swallowed. "So, it's going to be like it was. Like when we were between cases."

"Worse." Cas said softly. "After killing Cain… It will be worse."

"That's why it already started, isn't it."

"I think so."

Dean was quiet for a second. "Great."

"I'm sorry." Cas sighed.

Dean stared at his coffee, trying to ground himself. He forced his mind to wander, needing to avoid letting that sink in for the moment.

Focusing elsewhere didn't provide any relief however. He instantly became aware of the noise. The cabin creaking in the strengthening wind, the gentle taps of snow flurries hitting the window panes, the crackling fire. Each of these constant sounds somehow felt like too much on their own, the overlap making them unbearable.

He fought down another shudder with all his might, but it still snuck past his efforts, and he felt a hot flash of angry heat behind his eyes. He managed to blink that away for the moment, but he wasn't sure how long he'd be able to keep that up.

Dean glanced up at the clock, taking a second to count in his head. He frowned and after a few minutes he spoke. "You should eat something." He prompted again.

"I do not-"

"Cas, eat some fucking food."

Cas stopped, surprised by the tone. Slowly, he got up and walked into the kitchen, putting a bowl of cereal together before silently returning.

Dean waited until he was seated again, seemingly satisfied for the moment. "So how much worse are we talking?"

"I don't know. You're a demon now, which I think will only magnify your symptoms." He shook his head. "Worse."

Dean was hit with a particularly violent shudder. He closed his eyes while his brain struggled to catch up. "There isn't anything I can do, is there?"

"I don't think so."

Dean sighed, this time a note of frustration clearly showing through. "Just fantastic."

.

Dean didn't remember there being this much pain last time around. Every muscle in his body was taking turns pulling tight, and with each contraction came a searing ripple of fire that somehow caught him off guard no matter how many times it had happened.

He staggered when he was hit with another shuddering wave, forced to grip the back of the couch to keep himself upright. His knuckles blanched white from the strength of his grip, and he managed to only hiss through the pain. If he wasn't fighting so hard to contain it, he knew he'd probably be screaming.

He hadn't felt anything like this in years.

Nothing on earth had ever come close to the torments of hell. The human body just cannot withstand that level of pain. Without the aid of immortal damnation, the nerve damage alone would kill someone. If he were human now, this would be the withdrawal that finally did him in.

He did not have the benefit of a mortal body now, and he seemed cursed to ride this through fully conscious.

Cas meanwhile was trying to think of any way he could possibly help him. He watched the tremor devolve into full on shakes. An hour later he clocked the sweat coating the demon's brow. He knew this withdrawal couldn't kill a knight of hell, but he also knew Dean truly wished it could right now.

Cas had no way to ease his suffering. When Dean was human, he had helped any way he could. He held the hunter while he tried to sleep. He reminded the hunter to take care of himself. Dean had lost over twenty pounds those last weeks before the werewolf, and if it hadn't been for Cas coaxing him to eat what little food he could keep down, it would have been far worse.

Now no food, no glasses of water, no cool compresses or painkillers or whiskey could help. There was absolutely nothing he could offer that Dean couldn't metabolize quick enough it wouldn't make a difference. Instead Cas realized he was useless. The only thing he could offer is companionship, and right now Dean wanted nothing to do with that.

He tried anyway. "Dean-"

"Shut the fuck up, Castiel." Dean snapped immediately, straightening up from his hold on the couch. Cas closed his mouth, feeling a wave of disappointment at the hostility, despite the fact he expected it.

Dean stalked over to the kitchen sink, running the faucet and splashing himself in the face with some surprisingly cold water. Somehow it just made his splitting migraine worse. He muttered a curse before drying himself off with a coarse towel and turning to lean against the counter.

Everything was uncomfortable to touch. His shirt was too restrictive, his shoes too worn. Every surface he touched was too rough. Hell, his skin was too tight. These senses just added to the rest of his discomfort. The sounds of the cabin had amplified, fighting to compete with the ringing and rhythmic drumming of his pulse in his ears.

Beyond that, the lingering smell of coffee was bad enough, but underneath was the sharp odor of burnt onions, having blackened to a crisp after being abandoned the other night when he laid his hands on Cas. He knew Cas probably couldn't even smell it anymore, now that the pan had been thoroughly washed, but Dean couldn't get it out of his nose.

He found himself stalking across the wooden floor again, stopping near the furthest window to look out into the stifling darkness. In the summer, the darkness of night would be tempered with the glow of other cabins as people settled in for the warmer months. No one was insane enough to stay in their summer homes through the Iowa winters.

They shouldn't be either.

He felt the annoyance spark into anger, developing further into a white-out rage. He reached out, hand closing around the lamp on the table. He threw it with force, the glass shattering as it hit the wall. He stood there rigidly, looking at the debris, breathing heavily with the return of a far off look.

Cas calmly stood up. He lifted the wood and leather chair, navigating it to the upper landing and setting it safely behind the salt line. He had known this would be inevitable at some point during Dean's withdrawal.

Dean looked over at him when he heard Cas settle back into his seat. He felt a slight wave of numbness, feeling almost a whisper of disappointment, the distance finally registering. He sighed before turning and beginning to pace again.

.

Castiel was surprised to find himself waking up, not having intended to fall asleep. He straightened himself out, feeling his body protest the awkward position he had been in. He chose to ignore the new bruise forming where the wooden arm of the chair had dug into his ribs.

Slowly he looked around, trying to spot the hunter. Without the lamp the cabin was partly in shadow, the gentle glow of the fireplace not quite enough to fill the space. His eyes scanned the darkness, almost missing the demon against the back wall.

Dean was sitting on the ground, his head down on the crossed arms resting on his knees. Even from that distance the shaking was unmistakable, this time far more consistent than when Cas had last been awake.

Cas pushed himself from his chair, stepping down off the ledge and slowly approaching Dean. He was careful to make noise while he walked, trying to avoid taking the demon by surprise.

Dean looked up, unfocused gaze looking past him, face set in pain. "I have to breathe." He said, his voice a hoarse whisper.

Cas frowned, taking that in. He looked at Dean and guessed that not all of the shivering was caused by withdrawal.

"I'm freezing." He muttered, confirming Cas' suspicion. He looked up at Cas, something approaching desperation working its way into his eyes. "What's happening to me?"

"You're exhausted. You're weakened." He sighed. "Come on." He said gently. He reached down and slowly lifted the demon up from the floor. He kept Dean's arm over his shoulder, taking some of his weight as he guided them back towards the couch.

Dean was quiet, his body protesting the movement with searing pain. He allowed Cas to sit him down on the end of the couch nearest the fire.

Cas stepped over the salt line, grabbing a blanket and pillow from the bed and bringing them back with him. He put the pillow against the arm, sitting down next to it. He hesitated for a moment before reaching over and gently touching Dean's arm, coaxing the demon to lay back on him.

Dean allowed himself to be led, settling back unexpectedly against Cas' chest. He felt the blanket slide over him, adding another layer of protection against the arctic cold of the cabin.

Cas could hear the wind howling against the outside walls. Right now he was grateful for Sam's improvised insulation on the door, but even with that, the cabin was much colder than usual.

In spite of that, Dean slowly found himself warming up between the blanket, fire and Cas. The shivers of cold slowly eased themselves back into the intermittent shudders of detox.

Cas considered it before he slowly reached an arm down and across Dean's chest.

Subconsciously, Dean pushed himself up, repositioning into a less awkward position against him.

"How bad is it?" Dean breathed, his eyes on the fire, trying to get them to focus so he could ground himself.

"You are very close to human at the moment."

Dean felt the pain build before he could respond. The sensations crashed in on him with a violence he wasn't prepared for. He suddenly felt himself missing the burn he suffered hours ago as it was mild in comparison to this. The scream that was threatening to escape was quickly cut off with a strangled hitch, his vocal cords seizing up with every other muscle in his body.

Cas gently gripped Dean around the shoulders, carefully bracing him as his body went rigid, arching away from the pain.

After what felt like several eternities, Dean felt the tension give, the pain retreating into a more manageable level. He felt his chest finally unclench, allowing him to draw a gasping breath. He fell back against Cas, the episode leaving him exhausted.

Cas readjusted his grip, pulling Dean up and wrapping his arms a little tighter around him on instinct.

Dean swallowed, taking a second before he could muster up a rough voice. "Could it? Turn me human, I mean? Could I die from this all over again?" He paused. "Would it kill me for good?"

Cas tried to ignore the stifled twinge of hope when Dean asked that last question. "Even if your body acts human, you are still a demon. You cannot die from this."

Dean fell silent. He felt his head swirling, reeling with every sensation. Pushing the pain to the back of his mind for a few minutes offered no relief, his mind flipping through vivid memories of grabbing Cas the other night, fully unable to stop himself.

He just barely managed to push himself to his feet and half stagger half crash into the bathroom to be sick. When done, he finally sank down against the wall, feeling too drained to keep himself upright.

Cas slipped into the cramped bathroom, settling down next to him and extending a glass of water. He took it back when Dean was finished, setting it aside. "We should get back to the fire."

"Can't." Dean mumbled, letting his head smack back against the tile, igniting another spike through his head.

Cas stayed still for a moment before he let himself slide down next to Dean, pulling him against his chest in here instead.

Dean closed his eyes, clinging desperately to the feeling of Cas holding him, able to really feel it, feel like himself for the first time since he changed. He couldn't let go. He couldn't lose this. "Please. Cure me again. Let me fight it again. Just make me human. I can't-" his voice broke and he cut himself off.

Cas closed his eyes in pain. "We can't. If… if it doesn't work… you'll just have to do this again. It'll be just as hard again."

"Then please leave." Dean breathed. "Just leave me here alone. I'm going to kill you, Cas. I'm going to lose control and… please go."

"I'm not leaving you Dean." Cas felt the prickle of tears behind his eyes. "You'll control it. I'll be more careful. But I'm not leaving you here to go crazy on your own."

Dean shifted in his arms, pulling him closer. "I'm so sorry." he whispered, brokenly. "Cas, I'm so sorry…"

"I am fine." Cas soothed, resting the side of his face against Dean's head, his cheek burying itself into Dean's hair. He kept it slightly longer than he usually kept it, a choice he seemed to prefer as a demon. Just another in a long list of ways Dean was so starkly different than he was as a human.

The Dean in his arms was almost that man again. Cas just wished it wasn't just to suffer torment before it was ripped from him again. The universe was many things, but Cas was beginning to feel it was especially cruel of late.

"That can't happen again." Dean kept his gaze across the room, keeping it focused on the sink cabinet. "I mean it… I can't… please, I really can't hurt you again."

"You won't."

Dean dropped his eyes, unable to do anything but hope he was right. "I'm ready." He said softly. He knew the next blinding wave of agony was sure to come soon, and he didn't want to suffer it on the bathroom floor if he could help it.

Cas got to his feet, turning to pull Dean up as well. Cas steadied him as he stumbled, keeping close to him the whole way to the couch. He settled down again, more horizontal this time, Dean laying out further on top of him. "We'll figure it out." He murmured.

Dean held his breath for a second before letting it out in a half sigh. "It helps when I'm close to you."

"What do you mean?"

"When I touch the first blade… It is like something twisted and evil sparks through me, but it's a rush. It's weaker now, with the wards, but when I touch you… it feels similar… the same calm but… not dark at all." He shook his head. "I know why we can't, I just. It helped. Even if we don't touch, you do help just by being here."

Cas took that in. "When we touch it feels like… It's that strong?"

"Yeah." Dean breathed.

Cas shifted slightly, readjusting his arm so he could stroke his hand slowly back and forth across Dean's chest. He dropped it to lay flat as he felt the hunter suddenly tense again.

Dean strained, blacking out for one blissful second at the peak of the excruciating pain. When it released he lay gasping again, feeling like he was somehow more drained than he had been before, despite not thinking that possible.

Cas pulled his other hand up to run from his forehead into his hair, trying to impart any scrap of comfort he could. He decided continuing their conversation was probably the best he could do. "I have some ideas. For alleviating some of the confined feeling."

"Lay it on me." Dean quipped weakly.

"We updated the cuffs with the new wards. We could leave for a short time. If your brother helps to facilitate."

"It's not safe, Cas."

"No driving. We'll stay close to the cabin. There is no one anywhere near here." Cas assured him. "I'll be with you the whole time. While you will be restrained, I will not be."

Dean bit his tongue on a hundred ways it could go wrong.

"You need the tools to keep control this time." Cas pressed.

Dean winced. You need the tools to keep from hurting me again. "Yeah, okay."

"It will be okay. Kevin, Charlie… Sam… They have a few theories. You just have to hold on as long as you can."

"And if I can't?"

Cas turned so he could look at him. "I told you, you can."

"I don't-"

"Do you trust me?"

"Yes." Dean replied automatically.

"Then trust me on this."

Dean met his eyes, searching for any scrap of doubt and coming up with none. He couldn't help the tears as they came. "I don't want to lose this again…"

"I'm so sorry." Cas whispered, mirroring his hurt. He pulled Dean closer, pressing their lips together, ignoring the sharp salt from the hunter's tears. He let himself get lost in Dean for just a moment, his heart pulling desperately in his chest, feeling the acute mourning ahead of the upcoming events.

"I am too." Dean whispered back when they finally pulled away. He fit himself up under Cas' chin, laying his ear on Cas' chest. He took comfort in the slow steady rhythm of his heart, even as each beat sent another wave of pain rattling through his skull.

"You should try to rest before the next spasm builds." Cas prompted gently.

"Will I still be me when I wake up?"

"I don't know." Cas wrapped a hand around the back of Dean's head, holding him closer.

Dean breathed him in, hoping that a cure was coming, hoping that soon he could be himself again. Hoping he could come back to this. Come back to Cas, and Sam, and everyone who cared about him. Back home. Back to himself.

"Sleep. I'll watch over you."

Something inside Dean's chest relaxed, and he was able to take a deeper shaky breath. He closed his eyes, the familiar sentiment a comfort like nothing else was. "I told you." He mumbled softly, voice just above a whisper. "It's just creepy."

Cas managed a slight smile, settling his chin into Dean's hair. "Rest."