There are infinite possibilities, especially if we leave a lot of the world open to the current 'author's input.
If we went with the king idea, for instance, there are limitless possibilities of things that could happen. Court intrigue, dealing with individual issues and audiences with the commoners, warfare and political squandering- quite literally everything could happen.
I can work with whatever you guys decide to pinpoint as our setting and character though, so let's hear some ideas, eh?
The king/possibly-fantasy/medieval angle would be simplest in some ways and more complex in others, and yet something as simple as the day-to-day life of an ordinary human could suddenly become interesting as we create the social hierarchy and web around them and warp things into this complex social story. Science Fiction/Science Fantasy? Also incredibly worthwhile to delve into!
I can see this working out no matter what, dependent on our efforts, so I can be completely honest when I say 'I have no preference' in regards to the topics of settings and character xD