I think the penny dropped when it became clear one was an angel and one wasn't. When one had a career as a serial killer, the other an architect, when only one said he was from heaven (the tall one) and when the travel agent asked for 20 minutes with the tall fella and the short one wasn't having any of it. They're clearly an angel/demon couple, clearly haven't told anyone about their child and now heaven and hell will both be chasing them once word gets out. Really they're the best invention for the show.
I also really loved the Saint of Killers Hell reveal this week. This show continues to surprise in a way few other shows do. You could honestly do without the main trio, which I worry might be a concern in seasons to come. Tulip still hasn't got a scene that shows why she's lovable to Jesse, Cassiday hasn't had a scene that justifies Jesse's friendship, and this Jesse isn't the no-nonsense hero we loved in the comic.
I'm hoping that the Grail take center stage next season, and that a certain individual becomes a villain for the ages. Casting him will be critical. I have high hopes.