The shift in Dean's demeanor was almost imperceptible, and though they were no longer as close as they once were, Sam knew his brother. He knew his brother well enough to know that was not Dean.
Dean's eyes slid over to him with a look of detached interest and sick amusement.
And Sam knew. He should have always known.
"Michael."
"I did alright, didn't I?" he asked. "You and your brother had no idea."
"Why?"
He smiled and drew out his words as he said, "Oh, Sam, I'm not going to bother giving you an explanation you could never understand."
Sam tried to take a step back. He tried to get his body to do something, anything. He needed to get away and figure out a way to deal with this. He needed time to expel Michael.
But his organs were coated in a thick layer of ice and he couldn't feel his limbs. In a moment of fight or flight, his body chose to shut down, and that was just fucking great. Almost as great as his lungs struggling to suck in a single breath. It wasn't supposed to be like this.
Dean was supposed to be free.
Michael walked towards him with his hands behind his back, his motions seeming unnatural in Dean's body. Foreign and frightening.
"Thank you for letting me be a guest in your home, Sam," he said, a mocking smile spreading on his face. "But I think it's time for me to leave."
He closed the distance between himself and Sam and placed his hand flat on Sam's chest. "I hear the whispers of my brother awakening in the darkness while your brother screams in the back of his own mind."
A force pulsed through his body jerked Sam's head back and his mouth opened in a wordless scream. The intense heat that pulsed through his veins and every nerve reminded him of his time in the cage and the unending pain, the damage inflicted to his soul.
As quickly as it began, it was over. The pain faded into nothingness and Michael vanished with Dean.
A heavy thud drew Sam's attention to the ground, and he stared at… himself. His body with eyes burned out into bloodied, empty sockets and his mouth hanging open. A morbid captivation kept his gaze on his own body. The separation of his soul had been so seamless, he'd not realized it happened at all. It was like when Pamela let him and Dean roam around as spirits to prevent one of the seals on Lucifer's cage from being broken. As much good as that did in the long run.
Soon, the residents of the Bunker who'd come from the Apocalypse world would find his body. They'd mourn him, maybe. His mother would be devastated to lose both of her boys in one swoop, but she'd be free to live a life unconstrained by them. She left often enough that Sam suspected there'd be a modicum of relief for her at this. Not in a way that Sam could have held against her, but because that was who she was after being brought back. She was finding her place in a world where the boys she'd left as children no longer needed her and her husband was dead, along with most everyone else she'd known.
They'd put his body on a pyre wrapped in a white cloth, as if he deserved such a pure color to encase him for eternity.
And, soon, Billy would come to deliver him to the Empty. She'd take him to his final resting place, a place from which he could never escape. That would be it.
No more second chances.
No more soul selling deals.
He would be the man killed by an archangel in his brother's body.
Maybe that was fitting for the boy with the demon blood.
Maybe it didn't matter.
He spent his time in death the same way he spent his last moments in life: standing still. Frozen.
Useless.