Monarchs are a central feature of nearly all fantasy. No matter what there is bound to be a king or queen found running around somewhere. Monarchs may occupy the role as both hero and villain in fantasy, and in flintlock fantasy their overthrow may be a central theme. Knowing which form of government your monarch functions in will give you more options to flesh out your setting and create conflicts to move the story forward.
Since many stories take place in their world’s version of the Middle Ages we might as well start with the system of governance that was popular in Western Europe during that time. In these systems the king wont be much more then a wealthy landowner. It’s important here to remember that being king doesn’t necessarily mean anything. What the king is able to do will be limited by their ability to raise funds and convince noble landholders to follow them. You might also see a lack of well-defined borders, and lords of one country may be free to make their own treaties with lords of another.
Robb Stark struggling to keep the support of the Karstarks is a good example there being no guarantee that the king’s orders will be followed.
More powerful than a simple feudal king. An autocrat, at least in theory, wields absolute power. Nobles serve at their pleasure and their authority is backed up by the strength of their armies. All monarchies are beholden to the whims of the ruler, but in an autocratic regime where there are even fewer limits on the ruler’s power, the government will be especially vulnerable to the mood swings and fancies of its ruler.
We can expect these upheavals to be most evident shortly after a new ruler has come to throne and begins replacing their predecessors advisers with their own. If they had any ill-will towards their parents, this would become obvious as they begin to do away with the institutions built by their parents.
For a real life example you can look to the Russian Tsars. They were autocrats with many different styles of rule. Some even believe in enlightenment principles but excused their failure to enact them by claiming that they would never work in Russia.
The election may be a one time occurrence or a regular affair. A one-time election may happen following the death of the previous monarch. If no satisfactory heir is available to nobility may opt to chose one for themselves. This happens in Adalbert Stiftler’s Witiko and is also how the Romanov dynasty came to power in Russia. In other lands such as the Holy Roman Empire, electing a ruler was more routine. Elections could be bought by paying off electors or otherwise convincing them to vote for a particular candidate. By manipulating this system a single family can stay in power for generations even if the position in not actually hereditary.
At one point these rulers were likely autocrats or feudal lords, but since then their power has been greatly diminished. Constitutional monarchs have had their power limited by the imposition of constitution which outlines their rights and those of their subjects. Who wrote this constitution and the conditions under which it was written will ultimately determine the content. A constitution written to preempt an uprising will be far less generous than one pried from the king. What’s most important about these types of monarchies is not necessarily who the government gives a voice to, but who it does not.
Suffrage may be extended to the entire population or only select parts of it, but for our uses it easiest to assume that voting power lies in the hands of the wealthy landowners, nobility, or possibly members of the priesthood. At first the power of these voters and the limitations placed on the monarch may be relatively small. Parliament for example began as a way for the king to raise taxed from the nobility. But what this does is force the monarch to negotiate with the nobility when they need funds, and may be forced to make concessions in order to get their support.
Many rulers in our own history have claimed that their power is granted to them by gods, claimed relation to a god, or claimed to be a god. But in many fantasy settings it’s not out of the realm of possibly that you’ll find deities walking alongside your characters. A civilization ruled by an immortal demigod or an actual deity is going to have a very different political structure than any we’ve seen. How well will a revolution go if the monarch can call down hellfire to smite their rivals?
Every so often someone comes along and decides that they would make a better king than whoever currently sits on the throne. This person may or may not have a strong claim to the throne through family ties and will have come to power by exploiting a succession crisis or and incidence of weak leadership on the part of their predecessor. Once they’ve seized the throne the big question is whether they will be able to keep it. An usurper may seek to marry someone related to the previous ruler in order to legitimize their claim to the throne and generally look for ways to assert their legitimacy. Upon their death the legitimacy of their heir’s claim to power may also be in question.