Love is a common theme. Often, there is a romantic relationship between a human and the vampire king. Another theme is power. The vampire king has great power, and there are often struggles over it.
Well, mystery is a big one. The origin of the vampire king, his powers, and his secrets are often shrouded in mystery. Also, the theme of loyalty comes up a lot. The vampire king has his followers, and their loyalty is tested throughout the story. There can be betrayals and reconciliations, which add to the drama of the novel. And of course, the theme of survival in a world that is often hostile to vampires, even though the vampire king is powerful, he still has to deal with threats from hunters, other supernatural creatures, and sometimes even his own kind.
One of the main themes is the duality of the vampire king's nature. He can be both cruel and kind. There is also the theme of immortality and how it affects the vampire king's view of life and relationships. For example, in many novels, the vampire king may have seen countless generations pass by, which makes him somewhat detached yet longing for real connection. In addition, the theme of the supernatural world and its hierarchy is often explored, with the vampire king at the top or trying to reach the top of that hierarchy.
Forbidden love is also very common. Since the vampire king is in a position of power, his love interest may be from a different social class or species, like a human or a lower - ranked vampire. This creates a lot of tension and drama in the story. For instance, in many novels, there are rules against such relationships in the vampire world.
Power and responsibility is a common theme. Tsukune, as the Vampire King, has to deal with newfound power and the responsibilities that come with it.
Love is also a prevalent theme. It could be Finn's love for a particular character, or the love others have for him. Sometimes it's a forbidden love which adds an interesting twist to the story. Additionally, the theme of redemption can be found in some fanfictions. Finn may have done some bad things in his past as a vampire king, and the story could be about his journey towards redemption.
One common theme is the power dynamic between the vampire king and his mate. There's often a display of the king's dominance in the relationship.
Power and leadership are common themes. Writers often explore how Edward would handle the responsibilities of being a king, like making decisions for the vampire community.
Another common theme is power. Edward being a vampire king has power, and Bella's transformation also brings power. Fanfictions often play with how they use or struggle with their powers in relation to their relationship.
One common theme is power. How Harry's new status as a Vampire King gives him different kinds of power, both in the vampire world and in relation to the wizarding world. Another is identity, as he has to figure out who he is now that he's part vampire.
Control and manipulation are common. A vampire dictator in a novel would likely control the lives of those around them. They might manipulate humans for their blood supply and other vampires to maintain their power. Another theme could be the isolation of the dictator. Even though they have power, they may be alone at the top, with others fearing or hating them. For example, in many vampire stories, the vampire is an outcast from normal society, and as a dictator, this isolation could be even more pronounced.
Romance is a major theme. The love between the human (or whatever the main character is) and the vampire king drives the story. Another theme could be power, as the vampire king has a great deal of it and how it affects their relationship.
Well, leadership is often a theme. The king is in a position of leadership, and the story may explore what makes a good or bad leader. Also, there could be a theme of justice. The king is supposed to dispense justice, and the novel may show how that is done or not done in the fictional world. There might also be a theme of heritage and succession, as the throne needs to be passed on in an appropriate way.