A long time ago, Sam begged Dean to kill him.

But Dean knew better than to do that. Sam was a good kid. Kept his nose clean. He had the biggest damn heart he had ever had the pleasure of knowing. He felt privileged to be called his brother. But he felt burdened with the knowledge of the "inevitable" murder he would have to commit on the one person he would give his soul, (sell it to the devil, in fact), to protect. He couldn't bear it. Some days he thought that suicide would be the easiest fix: if he was dead, he wouldn't ever have to kill Sam, if circumstances came to that. But it wouldn't. Sam would always be the same. Dean could change, but never Sam. Sam was his little brother: younger siblings were always the annoying child they had been. Dean froze Sam's life when he was sixteen, and he wasn't ever allowed to grow any older.

But then Dean went to Hell, and, if Dean knew just how bad it would have been for Sam, how difficult it would have been for Sam to move on, he would have just let him die. Dying was better than living with your soul in Hell, after all. And when Dean was finally topside, something inside of him felt wrong. Something between him and Sam felt wrong, but he could never put his finger on what.

And then he found out about Sam's . . . extracurricular activities. He felt heartbroken, betrayed, frightened, angry, distant, but . . . loyal. Always with the damn loyalty. It would be the death of him, and it already had been. They made a deal - rather Sam spoke, Dean listened, and thanked the Heavens, (which he would regret later), that Sam felt the Sam way - but somewhere along the rode, he lost Sam again. He didn't know when, why, or how, but Dean knew he was gone. The thing was - the really fucking annoying thing - Dean didn't know how to help. He could help, he was sure of it, he could save Sam, but he didn't know how. He didn't know how.

And then Ruby, and demon blood, and doubt, and the goddamn angels . . . they ruined the brothers. It was a team effort. If some force were to take away the angels, the demon blood, and Ruby, all those heartbreaking factors, and that ever-remaining doubt, the brothers would still be standing.

But they weren't.

Dean was done with Sam, and Sam knew it. So he left. He hoped, prayed - to the God he had betrayed - that Dean would stop him. That he would say,

"No, Sam, don't leave. We can work this out."

And then Sam would smile on the inside, because this meant that Dean, somewhere deep inside, still loved him. That they could still be fixed.

Instead, Dean had agreed. Sent him off; watched him walk down the dusty road all by himself. He didn't stop him.

And when Sam found out that he was Lucifer's vessel: well, by God, that was reason enough to get the band back together. It was them against the world, (and Heaven and Hell), just the two of them. As long as they were together, the world still had a chance.

But Dean had other plans.

"On that basis alone we should just pick a hemisphere."

And that - that sentence right there - killed everything left inside of Sam Winchester. If he said yes to Lucifer, he would disappoint Dean, but why would that matter? Dean never wanted to see him again. There was no way he could redeem him in his eyes, so why try? He had this pit in his stomach, and it needed to be filled. If not with Dean, then, perhaps, on the off chance that Lucifer still needed him. . . .

But who was he kidding? The world couldn't end without Sam, and the world couldn't be saved without Dean. If Sam was willing, and Dean wasn't . . . Sam - Lucifer - would win. Hell would win. And Sam knew that there was no way Dean was going to say yes; it wasn't in his bones.

Big show-down in Detroit. And that was the last time Sam - the single being possessing his meat suit - saw Dean.

Dean watched with wide eyes - until the bright light would no longer allow him to stare - as Sam's body fell to the ground and Lucifer crawled inside. Dean couldn't move, couldn't breath: and then Sam slowly stood, coughing and shaking in the knees.

He looked up with his puppy dog eyes and muttered softly, "Dean?"

Sam's voice shocked Dean into motion, and he ran over to his brother, planting a hand on his chest and his shoulder. "Sam? Sammy? Are you okay?"

Sam cracked his neck and stretched his arm out in front of him, avoiding Dean's eye contact. "I'm - fine. I'm fine." Sam stared at his arms, closed his eyes and shook his head with a small smile. "Amazing." Finally, Sam turned to Dean, but he flashed uncharacteristically . . . un-Sam-like, (for lack of a better word), eyes into Dean's face.

Dean let his hands fall from Sam's body and he took a shaky step back. "Sam?"

Sam cocked his head, curiously watching as Dean stared, unable to look away from his brother's face. "Detroit," was all he said. "You've gotta love it."

"Sam, what the hell are you talking about?"

"Oh, I have Sam tucked in a nice little corner in here. He says 'hi.'" Sam's body smiled.

Dean's eyes widened as he realized just what was happening. "Lucifer," he stated.

Lucifer smiled, but then his lips fell. His eyes gazed about the room like he heard a voice, but couldn't find the voice's source. He held up his index finger. "Hold that thought." He closed his eyes and lowered his head, and Dean watched, unsure if he should run, or if fleeing would even be worth it. Suddenly, Lucifer flung his head back in laughter. "Dean, Dean, Dean. Sam sure does have some choice words for you."

Lucifer shook, and then Dean could see - right in front of him - the Sam-ish glint return to Sam's eyes. He blinked once, before setting his gaze on Dean. "Dean," he growled.

"Sam . . . Sam, what are you doing?"

"I said yes," Sam stated simply, his eyes fluttering about the room, taking in his surroundings.

"Why? You could have come to me, we could have fixed it. We could have made it right." Dean knew he was bull-shitting, but he was trying everything he could do to bring Sam back from the rails. However, he couldn't fathom that his brother had already jumped.

Sam laughed. "Oh, is that so? What happened to the 'we're stronger when we're a part' bit you spewed to me? No, I can't imagine how staying with you would have helped our chances. Besides, Lucifer and I," Sam tapped his chest lovingly, "We're brother's now." Sam glowered up at Dean. "So you can go running to Michael, if you want. But you won't." Sam began to pace the length of the room.

"You couldn't have called? Said you were having a tough time? I would have come. I would have helped you. You're still my brother." Dean's voice was soft, frightened, and full of emotion. For a moment, Sam almost let it get to him, but then he heard Lucifer's voice from somewhere inside of him say, He wouldn't have listened, anyway. It was right that you came to me; good that you came to me. I'm your big brother now. Right? Doesn't it feel right? I don't think he cares, Sam. I care, I do. I can help you, remember? It's just me and you. Against the world.

Sam laughed again. "Damn, Dean, I don't ever remember you being this damn funny," he spat. "I told you: I'm done needing you. You don't need to help me anymore, because I know you don't want to. I know you don't care."

"Sam, that's not true."

For a laughable second, Sam almost said, Well, Lucifer said it is, but that would make him sound not only like a five year old, but also like a scared little child afraid of being alone. Afraid of being let down, especially by his big brother.

So, in place of that nearly self-condemning sentence, Sam said, "You can deny all you want. But I, you - we: we both know that you're lying. I've been a burden."

Dean almost thought he saw sadness behind Sam's eyes, but it was gone just as nearly as it had appeared.

"But that doesn't matter anymore. Because now I'm not. So you don't have to worry. And neither do I."

"Sam, what are you talking about?"

Sam smiled. "You can't imagine it, you know. The power. If you were to tap into some of the limited intelligence you happen to have and said yes, you'd know it, too."

"I thought you weren't going to say yes? I thought you were tired of being a part of some over-rated, below-you, shitty master plan? Huh? Because that was what you said, I don't know, three days ago?" Dean sputtered, angrily.

Sam glanced over to Dean's direction and smirked. "I'm a ticking time bomb," Sam muttered under his breath, lowered his head, and stated to no one in particular, "Hey, Lucifer, lend me some mojo, would you? I want to prove a point."

Faintly, Sam heard Lucifer respond. I'll make you more than prove a point, Sam.

Before Sam had a chance to psycho-analyze this, he watched through the very top corner of his eye as Dean took a few more steps back.

Sam lifted his head and walked toward Dean. "Watch this." He snapped his fingers and the dimly-lit light fixture in the corner exploded.

Dean cringed, but quickly recovered and began chuckling bitterly at a joke that wasn't funny. "A lame-ass, low-level demon could do that, Sam. You could do more than that when Meg was possessing you. This isn't much of an improvement, if you ask me."

Sam only smiled. "In time."

"So, what's the plan now? Light the planet on fire? What would happen to you, then, Sam? You'd go down in flames with the rest of us who don't have your, uh, 'lent' mojo."

"I wouldn't worry about me." Sam cocked his head again and took another step toward his big brother. "Oh, and Dean," Sam grinned a sickly satisfied grin, "You're on my hemisphere."

The next thing Dean knew, he was forced up against the wall behind him with such powerful energy, he thought he felt the wall behind him crack. (Actually, that might have been his ribs, but he was too emotionally numb to feel the pain.)

He blacked out. The next thing he knew, he was running from Croats and he lost his brother to Lucifer forever.

There was nothing he could do.

So when 2009 Dean came around, he made sure to drill into his head exactly what he should have done. He should have killed Sam. A long time ago, before he unleashed Satan and began the end of the world.

But no. Dean could never do that. And he couldn't say yes to Michael. Even Lucifer knew that. He was stuck.

This time, there was no way out.