From the interview
Is it a pivotal episode in terms of taking Season 9 into the home stretch? I know you don’t want to give too much away, but do some of the bigger story elements take major turns?
Yeah. There are a few things operating here that I think are pretty essential. In the episode, we see the birth of Abaddon as we know her, and she is obviously a central nemesis this season and her role continues to grow. We have Crowley trying to recruit Dean, to help him or collaborate with him further. That plays out as a very, very important story line for the rest of the season. And we see Dean wrestling with the addiction-like jonesing that he has with the Mark of Cain and the First Blade, and the wedge that that’s driving between him and Sam. So there’s a lot of mythological groundwork that’s being laid in this episode.