Hellfire was hot.
Grace was hot.
The Darkness, though. The Darkness was cold. Ice.
It felt too much like Lucifer in his veins.
Sam knew from experience.
He felt it oozing through his body. He couldn't ignore it. Its icy fingers, so much more substantial than even Lucifer's grasping Grace ever was, felt like talons. They tore at his veins, froze his lungs.
It was difficult to breathe.
Reassuring Dean came too easily. He didn't say anything at all about the frozen nitrogen he was sure his blood had become.
After all, what would Dean expect?
Not images of Lucifer scratching at his peripheral vision.
Not cold emptiness replacing his blood minute by minute.
Dean wouldn't expect something like that.
(Dean was always too optimistic, Sam thought in a rare moment of bitterness. It was wiped away by the next howl from Lucifer's torn and bloodied maw.)
(Then all he knew was fear until Lucifer faded into the void that never left.)
The phone was dead.
Dean bought the lie.
Sam relaxed. The void almost overcame him. He focused.
He couldn't let this happen. He couldn't leave Dean now, not right after he'd gotten him back.
Lucifer giggled. Sam dug his thumb into his palm. The void clawed madly at his veins. He dug his thumb in harder, focused on the remembered pain.
Peace.
(He didn't know how long it would last.)
(The cold crawled further up his chest.)