Isolation can be another theme. Despite their power, demon kings may be alone or have very few they can truly trust. They might be feared and shunned by most of the world in the story, which can lead to their own internal struggles and character development.
Good vs. evil is also typical. The demon king is usually seen as the embodiment of evil, while the priest is associated with good, and the story revolves around their clashes or attempts at coexistence. For example, in some novels, the priest may try to redeem the demon king. This adds a layer of moral complexity to the story.
One common theme is the battle between good and evil. The hero represents good and the demon king represents evil, and they fight for the fate of the world.
Another theme is redemption or change. Sometimes, the demon king starts as an evil figure but through interactions with other characters, he may start to change his ways. For example, in some novels, the demon king may start to care about the well - being of his subjects more than just power. This can be seen in how he might make policies to improve the living conditions of the people in his domain. And also, the theme of mystery often exists. There are usually secrets about the demon king's past, or about the game world itself that gradually unfold as the story progresses.
Power is a common theme. As a great demon king, characters often have to deal with the acquisition and proper use of great power. For example, in 'Overlord', the main character has to figure out how to use his overwhelming power in the new world.
Innovation in construction is also a common theme. Given the demon king's often - otherworldly powers, he might use magic in unique ways to build structures. For instance, using dark magic to create impenetrable walls or using illusions to make the town seem more inviting. There is also the theme of redemption in some cases. The demon king may be trying to atone for past misdeeds by creating a great town.
A prevalent theme is redemption. Sometimes, the demon king may not be entirely evil, and there could be a chance for him to be redeemed, or the hero may have to struggle with his own dark side. Also, friendship and loyalty play a part. The hero often has comrades who support him, and the demon king may have his own followers. Their relationships within their respective groups are important aspects. In addition, the theme of sacrifice is often seen. The hero may have to sacrifice something precious to defeat the demon king or vice versa.
One common theme is redemption. The demon king, after a life of doing evil, now tries to make up for his past mistakes. For example, in many novels, he might help the weak or fight against other evil forces that are a threat to the world he now wants to protect.
Forbidden love is also typical. Society or the natural order in the story's world may not accept the relationship between a demon king and a non - demon. This creates a lot of tension and drama in the story. It's like Romeo and Juliet, but with a demon king twist.
The theme of isolation is also present. Being a demon king sets Castiel apart from others, and he often has to deal with being alone. Some fanfics show how he struggles with this newfound solitude and how it affects his mental state and decision - making.
Power imbalance is a big theme. The demon king usually has a great deal of power, and in the school setting, this can create all kinds of situations. Also, friendship is a common theme. Despite their differences, the demon king often forms unlikely friendships with other students in the school. They might start off as enemies but end up as friends through various adventures and shared experiences in the school.