WARNINGS: Major character death, implied dub/non-con, angst, end-of-the-world imagery, mentions of suicide attempt

A/N: Written for my hc_bingo square "planet distruction."

He'd thought, a long time ago, that when he said yes it would all be over. When he'd confronted Lucifer in Detroit, he'd been certain that one way or the other, it would all be over for him. He wasn't sure where his soul would go—Heaven, Hell, none of the above—but wherever it was, he'd been sure that it would be better than the waking Hell that was his life. He'd thought he had nothing else to lose, nothing left for the Devil to strip away.

He'd been wrong.

Maybe it was some kind of punishment for defying him for so long or maybe Lucifer truly enjoyed his company, but the oblivion Sam had been half-hoping for never came. There had been one instant, as Sam was engulfed by blinding white light, where he'd thought that it was all over. Then he'd felt Lucifer settle into place in his head, Grace rushing like fire through his veins, more potent than demon blood had ever been, and he'd realized it was just beginning.

"It's like being chained to a comet," Jimmy Novak had said, a long time ago. The poor bastard had been holding out on them. Sam still remembers how it'd felt when Meg possessed him; this is nothing like that. Sure, the basics are the same: trapped in his own body, forced to watch as his body becomes something alien to him, forced to feel the crush of bone beneath his fingers.

But Meg had never reached as deep into Sam as Lucifer can. He'd tried to fight back at first, and when that had proved useless, he'd tried to hide inside his own head, hoping to find a way to make himself oblivious to the death and pain around him. Lucifer had found him, dragged him out, and flayed him open. He feels as Lucifer feels, and the worst part is, sometimes he doesn't even know where he ends and the angel begins.

"This is your legacy," Lucifer says out loud, looking down on the ruins of New York City. Sam can still hear the screams, still smell blood and burning flesh on the air. "This what you were born to do."

Sam doesn't even bother to protest now. He's not even sure if it's a lie anymore: all he knows is that sometimes it just feels like it's him, Lucifer, and the end of the world.

Lucifer does put him to sleep sometimes, when he's brought news about Dean, or Castiel, or any of their friends. When Sam comes to again, Lucifer's mind is carefully blank. For all Sam knows, everyone he knows is dead, but he doubts it. Lucifer would never give up an opportunity to let Sam know that he's all that's left.

So, when Lucifer leaves him awake when the demon finds them, Sam knows it can't be anything good. The demon whispers a few words in their ear, and Lucifer lets out a soft huff of laughter. Sam feels like he's dying.

"Who'd have thought, huh Sammy? All this time, and your brother is still trying to end this."

Please, Dean. Sam's the closest he's come to praying in years. Please, just finish it.

Lucifer's soft brush against his mind is both reassurance and threat. "Now, now, that's not a very healthy attitude to have." The devil smiles. "If he wants the Colt, why don't we tell him where it is? Give him a fighting chance. We could even take it to him ourselves."

Sam swears at him, every filthy word that Dean ever muttered when he thought Sam couldn't hear. Lucifer just smiles wider, letting Sam go on for a full five minutes before he carelessly gags him.

"Save it for later, Sammy," he whispers. "After all, you want all your strength when we face your brother."

Sam fights against the gag, but it's hopeless. He settles for beating against the glass cage in his head. He's not sure if it's possible to give an angel a headache, but he's damn well going to try. He has to, even if he's beginning to realize that this nightmare is never going to be over.

Lucifer's putting on a crisp white suit, his fingers steady as he buttons the jacket. When he's done, he takes a second to run his hands down his body—Sam's body—in a lazy, proprietal gesture that makes Sam feel dirty, even though it's hardly the worse thing he's done with his borrowed skin.

"Big day today, Sammy," he says, turning slightly to see how the jacket hangs on him in the mirror. It fits him perfectly, which seems a little unfair, because Sam always had a Hell of a time finding clothes that fit.

Why? Sam asks. What's going on?

"We're going to have a little…family reunion."

There's a tingle on his back as Lucifer stretches out his wings, then a second of dizzying vertigo and they're no longer in the church Lucifer had been using a temporary base. Lucifer glances around, and Sam follows his gaze, taking in the drab gray building behind them, the rose bushes that are still managing to bloom.

Lucifer reaches out and plucks one of the blossoms, hissing as a thorn punches through the skin of his thumb. He licks the bead of blood off, and it's already healed. The small hope that Sam had had that maybe he wasn't as invulnerable as he'd thought fades. Lucifer sticks the flower in his buttonhole, and waits.

They hear the gunshots first. Dean's trying to be quiet, but he's trying to sneak up on an archangel. After that, it goes quickly. Sam fights against Lucifer's control, but it's like beating against a brick wall. He tunes out what Lucifer's saying in an attempt to concentrate, but he doesn't miss the way Dean looks at him, like all he's seeing is Lucifer and he can't even acknowledge that his little brother is still in there, screaming his name.

Then Dean's on the ground, their foot his on his neck, and when the Hell did that happen? They're pressing down, bone snaps, and Sam just…floats away. He's still tethered to his body, but he finds that dark place in his mind that Lucifer's kept him out of, and he just stays there. This time, Lucifer lets him be, and while he's dimly aware that something else is going on, all he can register is the way it'd felt when he'd snapped Dean's neck.

Dean's dead. Dean's dead, and he killed him. It's been a long, slow slide into darkness, but for the first time, Sam can believe that he's turned into the thing Dad warned Dean he might have to kill. It would have been so much easier if Dean had just followed Dad's orders—one time in his life that Dad wasn't full of crap, and Dean chooses to ignore him.

They're flying again, and when Sam gradually eases out of his hiding place, they're standing in the middle of a leveled city. He's not sure what city it had been, but it doesn't matter. It could have been anywhere; now it's nowhere.

"It's all over now," Lucifer tells him, and he sounds almost—sorry?

Please—Sam says, but he's not even sure what he's asking.

"He was the only one who had even the slimmest chance of stopping me." Yeah, that's definitely regret, and for a second, Sam gets a glimpse of the angel's emotions, of a love for his brother and father so fierce it hurt.

Michael will never come back now, will he? Sam asks. You killed his vessel, there's nothing left for him here. You broke the world trying to get his attention, and he still didn't come back.

"You don't know anything!" Lucifer's anger surges out of nowhere, and Sam instinctively shrinks back.

I know what it's like to have a brother. And I know what it's like when he turns his back on you.

Lucifer doesn't answer. The sun is setting, the smoke in the air turning the sky a brilliant blood-red. It really is just a matter of time now—how long the planet lasts depends on how much Lucifer wants to stretch it out. Sam's starting to wish he'd just get it over with.

"Do you want to go, Sam?" Lucifer asks finally.


"You've been here for the good part. The world has fallen by our hand, and all that. The clean-up part isn't nearly as fun."

You'd do that? You'd just let me go?

"Oh, I keep the meatsuit. It doesn't exactly need to have you in it, though."

Yes, Sam breathes. Please. It's all he's wanted for years now. Maybe it's the coward's way out, but he'd stopped caring about that a long time ago, sometime after the first time he'd put a bullet in his mouth, and woken up perfectly fine the next morning.

Apparently, Lucifer doesn't do goodbyes. One instant Sam's there, the taste of dust and burning heavy in his mouth, the wind lifting his hair, and the next, there's nothing but blackness.

There's something cool and metallic under his hands, and he's standing up. It all feels so real—the cool air against his skin, the smell of burning that's like an echo of a nightmare. Then the darkness is lit up by an incandescent shower of light that illuminates the clearing and the two figures standing underneath the falling sparks, and reflects dimly in the shiny black of the Impala. The taller of the two people turns, and Sam knows who he is even before he can make out his brother's features. He takes a few hesitant steps towards the car and Sam, and for a second Sam's sure that he'll vanish, or worse, that he'll look at Sam like he had the last time they'd met.

Dean starts to run, and for all that it could be a trick of the dim light, it looks like he's smiling. And for the first time in years, Sam finds himself smiling back.