In the end, what breaks Sam is the loneliness. He can't look to his left and count on seeing Dean, nor to his right and see Ruby, nor feel the amulet thud against his breastbone with every step.
Dean isn't dead. That keeps Sam going for two months. But Dean was in hell for four months (for forty years) and before that dead for six months, and this time Dean's learned what the Trickster wanted to teach Sam, and this time there's no hope of finding the Trickster and making him fix things.
It's appropriate somehow that it's November second when Sam finally decides that the world is going to hell no matter what he does. He can't just concede defeat, though; he's a Winchester.
It doesn't surprise him at all that, when he closes his eyes and raises the gun and pulls the trigger, he can open his eyes again. Lucifer is there, wearing Nick's body and holding Sam's gun and looking horribly disappointed.
"How'd you find me?" Sam asks.
"The sigils are on your bones," Lucifer answers. "Not your soul."
Sam nods; it makes sense. "Hypothetically speaking," he says, "if I say yes, what happens to me?"
"You remember the one you call Meg." Of course Sam does. "It would be much the same. But there would be no going back, and—it would be your choice whether you are awake for any of it."
"What about Dean?"
"That would depend on Dean."
Of course it would.
Sam hesitates a moment longer. "Something I'm curious about," he says. "Azazel. The other psychics."
"If Dean had never made his deal," Lucifer says, and of course he knows exactly what Sam wants to ask. Of course. "Jake would have been suitable. Stronger than Nick. Ava as well. The others—I told Azazel to seek potential vessels, but he was a nephil, not an angel. He could not have known their strength. Ansem, for example, could not have held an angel even as strong as Castiel."
Sam's pretty sure Cas is the celestial equivalent of staff sergeant at the highest. Sam bets this knowledge would burn Ansem's ass.
"It's genetic, isn't it," Sam says, thinking of Jimmy and Claire, himself and Dean. "Which of my parents—" He knows even as he's asking that it's Mom, that Dean saw Azazel home in on Mom and ignore Dad entirely except as leverage.
Lucifer smiles. "None of Azazel's other possibilities were children of two potential vessels."
Both of them. And everything Dean did in 1973—everything everyone has done between then and now—
(Inevitable.)
"I can't do this anymore," Sam says, looking away. "Any of this." I can't be alone anymore.
"Michael is my brother," Lucifer says, and Sam's gaze snaps back to him. "God was my father, and they both betrayed me, as your father did before he died, and your brother when last you spoke."
Sam nods. Of course. Of course.
"Don't hurt Dean," Sam says.
"I can't promise that. He does want me dead, after all."
"Not unless he's within two seconds of killing you."
Lucifer nods. "Not until then."
Sam takes a breath, steeling himself, and kneels. "I'll do it," he whispers. Forces it out.
The world goes white.
Sam stands—Sam's body stands; Sam is a passenger—steps over Nick's corpse, stretches in the familiar pattern of testing one's current physical capabilities. "Submission doesn't suit you," Lucifer says in Sam's voice.
Sam snorts, because wasn't that the whole point?
Please, Sam thinks. Just let me be done.
The world goes black.
