Sometimes, even for those of us who are the biggest Supernatural fans, it’s hard to imagine that, halfway through Season 12, there are still new stories to be told. But somehow, the writers continue to do it. And do it well. In “Lily Sunder Has Some Regrets,” we get a little of back story that we hadn’t heard before: Castiel’s.

“Lily Sunder Has Regrets” Recap:

This week’s episode kicks off in an arcade where we meet an angel named Benjamin (in a vessel that is a woman). Benjamin runs into Lily Sunder, a woman who is kind of badass, eye patch and all, and also happens to be immune to angel powers, and she’s out to get Benjamin. Benjamin uses angel radio to ask his old friends for help, but he doesn’t make the call soon enough and Lily kills him.

Meanwhile, at the bunker, Dean is trying to get a lead on Kelly (the Presidential aide pregnant with Lucifer’s baby). He’s also having issues with Cas after Cas broke Billie’s deal, potentially causing some “cosmic” consequences.

As it turns out, Cas has gotten Benjamin’s call since Benjamin was in Cas’s angel gang back in the day. Cas, Sam, and Dean head out to investigate. They meet up with the other members of Cas’s gang, Isham and Mirabel. The team is no longer huge fans of Cas’s, as it turns out, with the whole closing heaven and ditching them and all … They tell Cas that Benjamin is not the first of the team to have been killed like this, but they didn’t bother to tell Cas because they didn’t think he’d care. But, before they can properly air all their grievances, Lily arrives and kills another one of the angels, and she injures Isham before getting away.

So who are these guys? Who is Lily? Cue in flashback. Picture it: Orono, Maine, 1901. Cas, in the vessel of a woman (because of course he is), with his angel gang. They’re there to kill a nephilim, the child of an angel and a human (remember, the Rosemary’s Baby thing Kelly is pregnant with). Lily is the nephilim’s mother and is not about let the angel gang kill her husband and young daughter.

Cut back to today. As Cas and Isham stay behind so Cas can heal Isham, Sam and Dean head off to find Lily. Once they catch up with Lily, she shares a different version of events. According to Lily, her daughter wasn’t a nephilim, and her husband wasn’t an angel. Isham was in love with her, and it was Isham who killed her daughter in an act of revenge for her not loving him.

Dean rushes back to tell Cas, and Sam stays behind with Lily. She explains that the magic she uses is angel magic, having traded her soul for the knowledge. Each time she uses the magic, a piece of her soul dies. She also warns Sam that, once Dean confronts Isham, he’s going to kill him.

Sure enough, Dean arrives and tells Cas, who is weak from healing Isham, and is then promptly knocked by Isham, who also attacks Cas. Once Dean comes to, Cas is too injured for Dean to create the angel sigil. Just before Isham can finish off Cas, Sam and Lily show up, and a battle ensues. Cas ends up killing Isham, and he apologizes to Lily, telling her that, if she leaves and someday decides she can’t forgive him, that he’ll be waiting for her.

Cas and Dean makes their amends regarding their earlier tension. They move on to pose the question as to whether or not he should kill Kelly and Lucifer Jr. Not just a nephilim, but one that comes from Lucifer. They don’t know for sure, and Cas hopes they can find another way.