This is really lovely, particularly these lines: Dean’s never been the one to draw the lines, so it makes a weird kind of sense that he’s not the one crossing them either. To Dean all rules are arbitrary, except the ones Sam makes. It’s Sam who defines the parameters of their life, both in what they do and who they are, and Dean’s always been happy to follow him, as far as he would go and no further. Sam is poised above him, trembling, and even though it hurts to realise that for Sam this line is harder to cross than the ones that will surely come after, Dean won’t hold him back. He made the decision long ago to take this any way it was given. And the idea of hunting taking over everything is chilling and well done.