A 'brainwash obey me and only me' fanfic could be a very interesting and perhaps a bit dark concept. It might involve a character using some sort of magic or psychological manipulation to make another character obey them solely. For example, in a fantasy setting, a powerful sorcerer could cast a spell on a hero, making the hero forget their previous loyalties and only follow the sorcerer's commands.
In obey me fanfic, the theme of self - discovery for the player character is quite popular. As the character is thrown into a new and strange world, they have to figure out who they are in this new context. Also, the theme of redemption can be found in some fanfics, especially for those demons who may have a more complex or 'bad boy' image. Fanfics might explore their journey towards becoming a better version of themselves.
The plot could involve a character using some sort of magic or mind - controlling device to make others obey them. For example, a villain in a fantasy world might brainwash the heroes so that they only listen to his commands. This could lead to a lot of internal conflict within the brainwashed characters as their original values and loyalties clash with the new forced obedience.
Another plot could involve a power - hungry leader in a fictional kingdom. They use some form of ancient magic to brainwash their subjects to obey them and only them. This could lead to a rebellion plot where some characters start to realize they've been brainwashed and fight back against the tyrant.
A powerful wizard and his apprentices. The wizard, out of a desire for absolute loyalty, brainwashes his apprentices to 'obey me and only me'. The apprentices, who were once full of their own ideas and dreams, now have to struggle against this new form of control.
Belphegor is quite an interesting character to write about. His lazy nature and his past actions (like his initial hostility towards the player character) can add a lot of depth to a fanfic. Diavolo, the future king of the Devildom, is also fascinating. His grand plans for the Devildom and his interactions with the other characters, especially the player character, can be really exciting to write about. And Barbatos, his loyal butler with his mysterious powers, is also a character full of potential in fanfics.
The 'obey me novel' often involves a story where the protagonist is immersed in a world full of demons. There are various characters with unique personalities and powers. The plot usually includes elements of the protagonist's interactions with these demons, building relationships, and dealing with different challenges and mysteries in this otherworldly setting.
One popular 'leviathan fanfic' is 'The Leviathan's Call'. It has an interesting plot that delves into the world of the leviathan in a unique way. The characters are well - developed and the writing style is engaging.
In 'obey me novel', the main characters are the human protagonist and the group of demons. Among the demons, Mammon is known for his greed and his rather comical antics. Leviathan is the otaku - like demon who is into anime and games. There are also other brothers like Satan, Asmodeus, Beelzebub, and Belphegor, all with their own quirks and characteristics that play important roles in the story.