Author's Note: It struck me that Show made a point of showing us Sam cutting himself in the lab, and his hand was wrapped through the remainder of the episode (and in the preview) even though a significant amount of time had passed. And then I wondered why, which led me to write this.

Obviously here there be spoilers for 7.01. A couple lines of dialogue are taken from the episode and the preview for 7.02. The title is taken from the FFH song "Undone."

Disclaimer: I own nothing you recognize.

Come Undone

"I have to say, I think this is my best torture yet: make you think that you're free," Lucifer said with that familiar smile that made absolute zero look warm, "and then pull the wool off of your eyes."

Sam flinched harshly at Lucifer's abrupt pulling pantomime and the Devil's smile widened. Sudden movement had only meant pain in the Cage, and it was a learned reaction Sam just couldn't shake, especially not with him standing right there.

"You never left, Sam. You're still in the Cage." He winked and Sam's blood ran cold. "With me."

"You're lying," Sam bit out, shaking his head though his insides had clenched tightly.

"Sam," Lucifer tsked, "I promised never to lie to you. In two centuries have I ever broken that promise?"

Sam opened his mouth to deny it, to say of course he'd lied, that he was the Prince of Lies, but the words stuck in his throat. "Just because you don't want to hear it doesn't make it a lie, kiddo," Lucifer had loved to remind Sam, always sounding so much like Dean that it hurt worse than any other torture.

As if he could see the words dying an ashy death on Sam's tongue, Lucifer inclined his head and raised a teasing eyebrow. "That's right, Sammy."

The nickname was, as always, a mocking jab to the gut, but Sam ignored it.

"No," he said. That couldn't be true. It just couldn't.

It would break Sam so much worse than anything had before. The Devil reveled in breaking Sam, curling up inside him and gluing the shattered pieces back together with his tainted, poisonous Grace. But this… This might very well break Sam beyond repair. And Lucifer knew it.

Which was how Sam knew it had to be true.

It was like a flip had switched off inside him, leaving him a cold void that Lucifer would be all too happy to fill with pain and despair and fire and ice and wrong.

His hand throbbed sharply against the jar he was holding and he glanced down in surprise, having completely forgotten about the blood. He briefly considering hurling the jar against the wall in frustration; everything was spinning out of control, leaving him sick and dizzy. And if all of this wasn't real, then it wouldn't matter anyway.

But he didn't. Sam stared at the jar for a long moment, its weight deceptively heavy in his fingers.

What if it is real? a tiny voice in the back of his mind asked, barely audible against the blood pounding in his ears.

His hand throbbed again, more violently this time, and Sam bit back a groan. He'd cut it on glass shards the last time he'd been in this lab, nearly a month before and the cut had yet to heal. But with everything else on his mind, changing the bandage over his palm had simply been automatic after a lifetime of living with myriad injuries at any given time.

"How's the hand, Sam?"

Sam started, looking back up at Lucifer, who was watching him with a mischievous glint in his eye. Sam recognized the look; it meant nothing but trouble. For all of Gabriel's tricks, Sam had decided decades before, he'd had nothing on Lucifer. "Gabriel was my little brother," Lucifer had told him once. "Where do you think he got his tricks from?"

"It's fine," Sam snapped weakly.

Lucifer snorted. "It's trembling." He smiled again. "Not that I blame you, but still. I thought we were past the lying stage of our relationship. There's no point, after all. I know you inside and out, Sam."

Sam clamped his right hand over his wrist to stop the shaking, but the blood still sloshed inside the jar. He needed to do something… The jar was important… But Lucifer's presence was distracting and all-encompassing, cocooning him like a miasma, drowning out all his surroundings.

"You never left, Sam. You're still in the Cage. With me."

The words echoed through his head, flowed through his body, tainting him irrevocably, like Azazel's blood had.

"Your hand is proof, you know."

Sam blinked. "What?"

"Proof that I'm really here—that you never left," Lucifer clarified, crossing his arms against his chest.

"I…don't understand." This was new, but Satan's mind games were never simple, never the same. He changed the rules faster than Dean could down a greasy cheeseburger at a roadside diner.

Sam blinked, remembering. Dean. He needed to get the blood to Dean. For Cas. To get the monster souls back to Purgatory. But Lucifer was speaking and he'd learned the hard way to pay attention to the Devil's words. Sam had a stubborn streak the size of Kansas but Lucifer didn't like being ignored.

"A simple cut like that should have healed weeks ago. But you're the expert on human first aid so you knew that."

"So what?"

Sam's palm throbbed yet again, the pulse beneath the skin burning like a poker thrusting into his hand. Sam winced and practically slammed the jar of blood down on a nearby shelf. He was going to drop it at this rate and the whole ritual to save Cas would be pointless.

If that was real, anyway.

Which Sam was having serious doubts about at the moment.

He glanced at Lucifer, who nodded. Sam pulled the bandage over his hand and hissed at the inflamed skin. His palm was bruised in mottled greens and purples, radiating from the angry red gash in the center. The smell of decay wafted up from the wound. A small trickle of blood leaked out of the corner of the gash and Sam stared, mesmerized, as it trailed his lifeline—there was something appropriate about that, Sam couldn't help but think—and dribbled down his wrist. The blood dripped onto the floor, leaving a faint red path on his skin.

Sam realized he was shaking again. He'd never seen an infection like that before.

He looked back up, eyes widening as realization hit. "You…"

"That's my mark," Lucifer confirmed. "No matter where you go or what you do, I'm always with you."

The truth of that hit Sam like a blow and the room spun in front of him for a long moment. It was like he was back in that motel room in Oklahoma with Lucifer telling him he was his vessel all over again.

"I will kill myself before letting you in."

"And I'll just bring you back."

That same helplessness washed over him. He was trapped with no room to move, to escape. Marked as the Devil's all over again in a never-ending cycle of wrong. It was just too much.

"Why?" he whispered brokenly.

It was his default question ever since childhood. Dean swore that it was his first word—that or no—and he'd started asking questions as soon as he'd been able to form sentences. At first it had been about why they moved around all the time or why they didn't have a mom or where Dad went. Once he'd started school, he asked even more questions, sure that Dean would know the answers because his big brother knew everything. Dean had hated it, but he'd always given him some kind of answer—ones that Sam would learn were lies a few short years later.

After he'd learned the truth about the family business, he'd been so angry and betrayed that he'd done nothing but question Dad's orders or why Dean would follow them. He'd been asking why nearly until the moment he'd walked out on Dad and Dean for Stanford. Why couldn't they support what he wanted for once? Why couldn't he have something normal after all this time? Why couldn't they understand?

After Jess had died, the whys changed but never left. Why Jess? Why me? Why Dean? Why now? Why?

In moments he'd forgotten even his own name in Hell, he'd only been able to ask why. And Lucifer had always been ready with an answer—as if he'd been waiting for the question. And this time was no different.

"Because you're mine, Sam," Lucifer nearly growled and Sam failed miserably to hide another flinch at the dangerous, possessive tone. "You've always been mine and always will be."

Always.

Sam swallowed. He could feel sweat beading on his forehead. "If that's true, then why keep up the game?" He shook his head, trying to logic the situation. Logic was all he had ever been able to turn to when the world was going crazy around him. "Why not end it?"

Because then he'd at least know for sure what was real, know that the last two years had been nothing but hallucinations meant to break him.

At least he could break knowing.

"End it?" Lucifer sounded genuinely surprised at the thought. "That's not how this game works."

"What do you mean?" God, Sam was so damn tired by all of this.

Lucifer smirked, his face lighting up with shadows as only the Devil's could. "You not knowing what's real? Man, that's the sweet spot. Why would I end it?" He shook his head, like a teacher explaining something simple a particularly slow student. He always knew how to pick at Sam's need to explain things, to get at the logic. "It ends when you can't take it anymore."

"Until I…?" Sam was pretty damn sure he didn't have anything left to give at this point if all of this really was fake.

His mind briefly went to the moment he'd walked into Bobby's living room after waking up to see both Bobby and Dean alive. He could almost feel his brother's arms holding onto him for dear life. It had seemed so real, so Dean. There could be no substitution for his brother, Sam had been so sure.

He'd always been able to tell when Lucifer or Michael had taken Dean's face before.

But maybe Lucifer wanted him to be able to tell for all those years. He knew what spending so much time with his brother would do for Sam. And what pulling the rug out from under him would do as well.

His hand pulsed angrily and he clutched it to his chest protectively. Heat from the infection seeped through his shirts to his skin; Sam wouldn't have been surprised to find a blister from it.

"This game," Lucifer said with a nod, "is all up to you, Sam. So go ahead, play at little brother and big bad hunter again. Play at rescuing your pet angel from himself and sealing the leviathans back in Purgatory. For now. But I'll always be with you because all of this is mine. And don't you forget it."

And then he was gone.

Sam nearly fell to his knees on the spot, his legs wobbling beneath him, but grabbed onto the nearby shelf to steady himself. He took a couple breaths to collect himself as best he could—which, it turned out, was not all that well.

He froze at the metallic clank of approaching footsteps. That had to be Dean, looking for him and the blood. Or Lucifer's version of Dean, anyway. Sam shook his head, but only succeeded in plastering his bangs to his damp forehead. He couldn't see Dean right now…real or not. He needed space, to be alone, to be anywhere but here.

He brushed his hair from his eyes and grabbed the jar of blood from the shelf with his good hand. He took a couple steps into the hallway as the footsteps got closer. He swallowed and put the jar on the ground where Dean would be sure to find it. Just in case.

And then fled in the opposite direction, rounding the corner and running blindly away.

"Sam!" he heard Dean call from a distance, but Sam couldn't…

Not when Dean's face in his memories kept morphing into Lucifer's, a cold smirk twisting his face in a way Dean never could.

"You're still in the Cage. With me."

"That's my mark. No matter where you go or what you do, I'm always with you."

"You're mine, Sam. You've always been mine and always will be."

"I'll always be with you."

Sam covered his ears with his hands and ran.

- fin -