One theme could be cultural clash. If the political marriage involves different demon clans or different species, there will be differences in their cultures, traditions, and values. This can create a lot of conflicts and plot developments. Also, redemption might be a theme. Maybe the demon king has done some bad things in the past, and through this political marriage, he tries to redeem himself and change his image in the eyes of others.
The demon king, of course, is a central character. His character is usually complex, being powerful yet having his own weaknesses. There is also the bride or groom in the political marriage. They could be from another powerful demon family or a different species. And there are often advisers around the demon king, like his most trusted demon lords or sorcerers. They might give different opinions on the political marriage, some for it and some against it.
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.
Power dynamics is a common theme. Since it's a political marriage, the fanfictions often explore how Fem Naruto and her partner balance power between their respective villages. Another theme is sacrifice. Naruto usually has to sacrifice some of her personal desires for the good of the village. For example, in many of these stories, she has to give up her freedom to some extent.
A major theme is the change in Naruto's identity. He goes from being just a ninja to a key figure in political alliances. His new status affects how others perceive him and how he perceives himself. Another common theme is the relationships within the harem. There are often rivalries, jealousies, and deep friendships among the members of Naruto's harem, which add drama to the story. Also, the theme of the impact of these political marriages on the overall Naruto universe, like on the balance of power and future generations, is frequently explored.
Power dynamics is a common theme. Since Naruto is godlike, it often shows how his power affects the political marriage, like whether it gives him more influence or causes tension. Another theme is loyalty, as Naruto has to be loyal to his partner and also to the political alliances his marriage represents.
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.