I know! I just watched that- holy crap! I did not think they were going to go there. I honestly just did not expect that even slightly. It sort of debunks my personal hope that the Lucifer=Sam and Michael=Dean equation could be swapped around and either brother could take either role, but it was still just an awesome premise for an episode.

There was one shot towards the end (either getting to or leaving the angels' hideout) where the camera is looking at Sam and Dean from the back of the car, like there was someone sitting in the backseat, and it was just a clear visual moment of what Adam would be seeing if he had lived and stayed with them. It's alienating and kind of off-putting, but it's a great shot and I wanted desperately to point it out to someone.