Nationality is meaningless on a deep enough level. Nations are only recognized by the executive functioning parts of our brain, not the deep tribal loyalty reptilian parts. People are loyal to their own tribes and studies confirmed that there is no "true" altruism but selflessness is naturally selected to promote one's genetic heritage. People are more likely to be altruistic to their own group, explaining why rich politicians serve other rich people and not the rest of America.
This executive function/reptilian brain segregation is also why people roll their eyes whenever people use the term "Americans" or "we're all American citizens" since it oversimplifies and disrespects the fact that America is composed of many different cultures and the fact that people are loyal to them. It's also why America feels like it may as well be run by aliens with alien values, the owning class culture and working class culture are vastly different. Even the English spoken by the two metagroups is different. This is why America feels like a place where everyone fights for their group's interests instead of the nation as a whole, other kinds of Americans aren't "really" recognized as their Americans.
There were even laws written in the South saying blacks had to give whites unwarranted respect, like giving up your seat for a white on the bus (what did that white even do to deserve such respect anyway?) People would say blacks are rude but if a group is morally excluded, even by law. You're giving them a right to be a... "jerk" since in all probability they'll be "disrespecting" a racist jerk who thinks they're less than them anyway. Moral exclusion is rooted in viewing others as the "other" and not worthy of the same kind of basic respect members of your group are. People treat you differently based on how you dress or speak.
When writing bad guys who are royalty an excellent way to do so is having them insist upon being called your highness or majesty if someone forgets to use such honorifics. The Princess of Druidia in Spaceballs was just a snob so there are exceptions to the bad guy rule however, but works very well to make the character less likeable.
I feel bad for the people of planet Earth - they've never had a galactic chess champion :(