Spoilers up to and including "On the Head of a Pin"
When Alastair hurts Dean, it feels like home.
When he punches him, flings him, shoots him full of rock salt, it feels so achingly familiar that Dean almost cries with the relief. He hadn't realized that the thing he'd been missing, the gaping hole he was trying to fill ever since being dragged out of Hell, could have been....
He'd spent forty years with him, forty years as a soul that didn't need food, didn't need sleep, just spent every single moment awake, aware.
When Alastair spoke to him, looked him in the eyes, into his soul, and spoke to him as if no one else mattered, as if surrounded by angels, and reapers, and whoever else they could still have privacy, it went straight to the pit of Dean's stomach. It pulled and twisted at parts of him that he thought Castiel had buried, as surely as Dean's body had been in the ground. It tugged them up to the forefront of his mind, until it was all Dean could do to keep them off his face.
What wasn't familiar, what was sick and wrong, was being on the other side of the rack--being the one standing there, torturing Alastair. As much as it stirred his groin, sung to his darkest desires, it wasn't a temptation. Even when Dean was learning, was embracing the darkness Alastair fed him, he hadn't ever tortured him. They'd hurt each other, yes, had torn each other apart, bathed in each other's blood. But that had been about pleasure, about the sweet burn of split flesh and the horrified looks of the newbie souls on the racks before them, unable to fathom what the two demons were doing.
Dean knew what Alastair was doing the moment he opened his mouth--his words, mixed praise and obvious mockery, egging Dean on to do his worst. It was Alastair the teacher, Alastair the mentor that was behind it. It was the Alastair who couldn't bear to watch his favorite fail, even if it was failing at torturing Alastair himself.
And as Dean watched Alastair bleed from his blades, melt under the holy water, he knew they were both wishing for the Pit. Reality was confining, Earth was denying them the true beauty of Dean's work. So Alastair kept pushing, kept talking, even as blood gurgled from his mouth.
Alastair's words were painful, tore at what little spaces in Dean's soul hadn't already been feeling despair. It felt right. And then Alastair's hands were own him, his fists, the pain, so familiar. Dean felt the world slipping from view and knew that he was going back, that he'd be back in Hell, that Castiel wouldn't come for him again, not as dirty as he still was, not with the other angels questioning them both. Soon, Dean would be back with Alastair, as his life slipped he could feel the hilts of Alastair's razors in his hands, the blood running between his fingers.
That, too, felt like home.
