It has taken me a few days but I realized what has been holding me up: the introduction of the heir to one of the five thrones. I already know what he is going to propose and what he is going to do. However, I realized last night I don't know how best to introduce him. Or rather, how my antagonist will be introduced to him.
This is what I need to figure out so I can continue. I've been toying with the possibility of adding his introduction as the new ending of Chapter 11. This may work. If not, at least trying it out should provide a glimpse of how it will work.