User blog comment:Rafe Adler/"Let the Good Times Roll" Discussion/@comment-31057575-20180518082315/@comment-1031724-20180520180913

Crowley was king of hell and Sam and Dean's ally at the same time, though he was less reliable than Rowena is now. But, who knows? Maybe they'll explore the white-eyed demons and give them a title. Alastair showed Lilith wasn't the only one. They already revealed three more yellow-eyed demons, identifying those as Princes of Hell, and then there's Knights of Hell like Abaddon, what do you call the White-Eyed Demons? (Not kings of hell, though technically Lilith was queen of hell after Azazel's death)

As for demons assassinating Rowena: She'd just come back with her resurrection spell, unless they "spawnkilled" her when she came back before they could do it again. Besides, Sam's destined to kill her for good, unless her redemption changed that. I still wonder how that'll turn out now she's officially on their side.