If there's one thing that can be said about King Birtram, it is that he is a man of duty. Anyone who is willing to wake up at 5 o'clock in the morning and sign paperwork in his bath must be either extremely self-disciplined or just plain crazy. And little Eric, too, is one dutiful dude—sacrificing his own safety to keep the Kingdom of Binn safe. And that's just it: in The King's Stilts, doing your duty means making some tough choices and finding the right balance between what you need, and what everyone around you needs.
Q: If he's the king, why doesn't King Birtram just do whatever he wants?
A: Probably because he wouldn't stay king for very long. See, there are these little things called coups…
Q: Why is it the king's job to keep the kingdom safe?
A: Well if it ain't the king's job, whose job would it be?
Q: Why does Eric feel like he has to help the king at the end?
A: Because he's a little smarty-pants and he knows to do the right thing.