What was your favorite plot thread in the BoD that literally never had a resolve or pay off?

Mine was the Fey Queen feeding Lyra from her breast.

It seems like the Secret Commonwealth likely is tied into this. And I love theorizing about who Lyra becomes and her importance in the HDM trilogy in regard to this scene and the milk. The Magisterium would have had a field day to learn that the "Eve" of their prophecies was fed from (in their eyes) a demonic beings tit as a child.

What's yours?