Ciel and Sebastian are usually the most popular. Ciel with his cool and calculating demeanor, even in a high school setting, is quite appealing. And Sebastian, with his charm, loyalty to Ciel, and his many skills, always draws a lot of attention. People love to see how they interact with the high school environment and other characters.
Undoubtedly, Ciel and Sebastian top the list. Ciel's leadership qualities and his determination to succeed in this high school world, which is full of new challenges for him, make him a favorite. Sebastian, on the other hand, is adored for his effortless elegance, his ability to handle any situation, and his unwavering devotion to Ciel. Their relationship in the high school fanfic is what many fans look forward to exploring.
Lizzie could be a popular cheerleader - type character. She's always trying to get Ciel's attention and is really good at sports. But she also has a bit of a temper when it comes to other girls getting too close to Ciel. And then there could be a new character, a shy transfer student who gets caught up in the drama between Ciel and the other students, and she has her own special abilities that she's not aware of at first.
Ciel is definitely one of the most popular. His complex personality and his tragic backstory make him a great focus for fanfiction. Writers can explore his inner thoughts and feelings more deeply. Sebastian is also very popular. His demonic nature and his loyalty (in a rather twisted way) to Ciel are fascinating aspects to write about. Grell is another popular character. His flamboyant and somewhat deranged personality offers a lot of room for creativity in fanfiction.
William T. Spears is also quite popular. His strict and no - nonsense attitude provides a great contrast to other more chaotic characters, and fanfiction often plays with his interactions with other reapers or the main Black Butler characters.
Onua might also be popular. He's reliable and strong. In high school, he could be the go - to guy for any problems. If someone needs help moving heavy things for a school event or needs protection from bullies, Onua would be there. His quiet strength would earn him a lot of respect and popularity among the students.
Grell is quite popular as well. His over - the - top personality and his unorthodox views make for some really entertaining reaction scenarios. He can go from being overly dramatic to having some surprisingly deep insights in fanfiction.
Ciel Phantomhive is often paired with the twins in fanfiction. Since he is a central character in the Black Butler series, writers like to explore different dynamics between him and the twins, such as a power struggle or a forced alliance.
In addition to the main characters, characters like Finny, the gardener with his superhuman strength, can be interesting to feature. Fanfiction can explore his backstory more deeply, like how he got his powers and how he copes with being different. Bardroy, the chef, is also a character that can add a lot to a story. His military past and his rather unique cooking skills (or lack thereof) can be a source of great stories in fanfiction.
Sebastian is often very popular. His demonic charm and loyalty to Ciel, despite his ulterior motives, make him a fascinating character to write about. Fanfiction writers can explore his internal struggles between his demonic nature and his growing attachment to Ciel.
Vegeta is also popular. His prideful and brooding nature would be really interesting in a high school environment. He might be the loner who's secretly really powerful and has a soft spot for a certain girl at school.
One interesting plot could be the main characters adapting to high school rules while still maintaining their unique 'Black Butler' characteristics. For example, Sebastian might use his skills to excel in home economics class, making perfect tea and pastries. Another plot could involve the students uncovering a mystery within the high school that has ties to the supernatural world, just like in the original 'Black Butler' series.