The next oldest, who thinks his mother's superior birth should trump the oldest brother's older status, is about to revolt. Taking advantage of a superstition that a king without brothers to support him is bound to loss.
I know what happens after -- including the oldest brother's revealing yet another brother in the mess -- but first I have to put in the point where the next oldest has him almost at his mercy, until he manages to escape -- alone and without any ally.
Still got to work out how he corners him.
Hmm -- maybe I could put that foreign wizard to work. Was thinking I was using too little of her.