[Revenge, not just for humans]
A Cas-centric episode with more angel drama. It's a trend that no matter which angel we come into contact with, they're all going to be uncaring toward humans and basically vengeful toward their family. However, it was really nice to get to see Cas in his former vessel and how he was as a soldier back in the day. Nephilim are an abomination, so they have to kill them, with no care for the innoncence of the child. The dynamic of how he acted back then to what he's facing now, with the potential of Lucifer's child, will be interesting. I doubt he will be so quick to kill.
But, of course, nothing is as straight-forward as "has mission, complete mission" when it comes to this show. Not only did Lily survive on Enochian power, but she had a reason for targeting and killing the angels that she did. They destroyed her life by killing her husband, as well as her child. But their mission was ill-guided, as Ishim lied (surprise!) and actually killed an innocent human child because of his perceived betrayal of Lily and her love. I have to wonder, as Cas has gone two weeks in a row killing cosmic beings, what the ramifications of his actions will be. He seems to be in a fatalistic mindset, though. He will go to any lengths to protect others, even if it means sacrificing himself. I'm sure Billie's death, at least, will cause problems for the Winchesters.
The drive out and the tenseness between Dean and Cas was interesting to watch. And poor Sam in the middle. It's not my pairing, but I can see how Dean/Cas fans can see the undertones with the way they're playing this. But at the heart of it is the deep devotion Cas has for the Winchesters and, in turn, how Dean and Sam feel he is family. And if they don't stick together, they're not going to make it through the ever-growing list of problems. Lucifer's kid, the British Men of Letters, the ramifications of killing Billie...the list goes on. Angels aren't going to help them now, only one angel, and that's the way it will always be.