Love and loyalty also tend to be common themes. The sister and Ciel may have a deep bond of love and loyalty. This could be tested in various situations, such as when facing enemies or difficult decisions. Writers might explore how far they would go to protect each other and how their relationship evolves over time in the face of different challenges.
Another theme might be mystery. The sister's existence could be tied to some hidden secrets in the story's universe. It could be about uncovering her past, her connection to certain events or characters, and how she affects Ciel's own journey which is often filled with mystery already.
One common theme is struggle. Ciel's fight against his asthma, both physically and emotionally, is often depicted. For example, he might struggle to keep up appearances in public while having an attack.
Adventure is also a frequent theme. They might embark on a journey, whether it's through a magical land or a dangerous city. This allows for a lot of character growth and exploration of their relationship. Also, loyalty is a theme that pops up. It shows how they stay loyal to each other through tough times in the fanfic storylines.
Another theme is the power dynamic between them. Ciel is the master, but Sebastian has his own power. Fanfics play with this dynamic, sometimes showing Ciel trying to assert more control or Sebastian subtly influencing Ciel. For example, in some fanfics, Ciel may try to break free from Sebastian's influence while still relying on him. It makes for very interesting reads.
One common theme is rivalry. Ciel and Alois are often pitted against each other in these fanfics, competing for power, status or just simple dominance.
A common theme is friendship. Many fanfics focus on how Ciel and Chamoisee become friends and how that friendship evolves. For example, they might start off as strangers and gradually learn to trust each other.
One common theme is mystery. Given Abberline's detective role and Ciel's often secretive nature, fanfics tend to explore the mysteries around them. For example, they might be trying to solve a crime together or figure out a mystery related to Ciel's family.
There's also the theme of friendship in some fanfics. Despite their differences, some stories show them gradually becoming friends. This usually involves them learning to understand and accept each other's past traumas and current motives, which is a very interesting and heartwarming take on their relationship.
A common theme is family loyalty. The sister is often portrayed as being extremely loyal to Ciel and the Phantomhive family. She will go to great lengths to protect their reputation and their lives.
The theme of power dynamics is quite common too. In undertaker x ciel fanfic, we often see how the power balance between them shifts. Ciel, as a young noble with his own authority, and the Undertaker, with his unique skills and knowledge, interact in ways that show a constantly changing power dynamic. And there's also the theme of trust, as they have to learn to trust each other in many of these fan - created stories.
In Ciel x Pluto fanfics, a frequent theme is protection. Since Ciel is in a rather dangerous world, Pluto's role in protecting him can be a central part of the story. Also, the theme of mystery might come up. Pluto has his own mysteries, and how Ciel deals with those or tries to uncover them can be an interesting plot in the fanfics. There could also be themes related to power dynamics, as Ciel has a certain power over Pluto, and this can be played with in different ways in the stories.