"Well, at least you showed up." Nick shrugged, sat back in his side of the booth, looked at Sam for a long moment. "Alright, so. The entirety of this story? Gets a bit winding around, so I'll need you to stick with me."
He tilted his head, studying Sam. "You contained him because the Winchester bloodline was meant to be vessels. You were meant to be Lucifer's all along and I was informed that I was picked at random, literally just a name from a phone book. But... the more I thought about that, the more I realized it couldn't be true. Even downing the demon blood that I was downing -- ugh, rancid -- I shouldn't have held up that long. The improvements that Crowley did on me to make me a permanent vessel? Shouldn't have worked the way they did. So why did it all hold up? Why did I last?"
He rested a hand on the table, one finger tapping idly. "Turns out we have some things in common."