Jester is a Desolate One who troubles the World.
One can only defeat so many villains that want to "cover the world in darkness" before one starts to look for a different flavor of horrible.
EVIL JUST GOT EMO!
Unbeknownest to the character, he is in the royal bllodline. Suddenly the majority of royals fall ill and die, and the hero is left with the crown, but no experience or idea of what to do.