A less common but still interesting theme is role - reversal. Some fanfictions might have Elizabeth taking on a more active or dominant role, perhaps in protecting Ciel or being involved in the more dangerous aspects of his world. This can bring a fresh perspective to their relationship and the 'Black Butler' universe as a whole.
Love and devotion are very common themes. Most fanfictions focus on how deeply Elizabeth loves Ciel and vice versa, despite all the difficulties they face.
One common theme is loyalty. Sebastian is Ciel's butler, and in many fanfictions, this loyalty is tested in various extreme situations. Another theme is power dynamics. Sebastian has supernatural powers while Ciel has his own form of authority, and how they balance or clash with each other is often explored.
One common theme is the exploration of power dynamics. Sebastian is a powerful demon and Ciel, even as a female in these fanfictions, often has her own form of power, be it through her position or her own wits. Their relationship is often a dance of power, with Sebastian being dominant but Ciel trying to assert herself in different ways.
Romance is also a big theme. A female Ciel might be paired with different characters in new and interesting ways. It could be with Sebastian in a different dynamic than in the original, or with other characters from the 'Black Butler' universe. Writers often explore how a female Ciel's relationships would develop in terms of love and friendship.
One common theme is mystery. Given Ciel's own mysterious nature in the 'Black Butler' series, many fanfics incorporate mystery elements into the relationship between Ciel and the reader. For example, the reader might be involved in solving a mystery alongside Ciel.
One common theme is love against all odds. Their different social standings and the situations Ciel is often in make their relationship a struggle, but love perseveres. Another is the theme of loyalty. Elizabeth's loyalty to Ciel and vice versa is often explored.
Well, a frequent theme is the exploration of Ciel's femininity. It might be about how she balances her female identity with her role as the head of the Phantomhive family. Also, there's often the theme of how other characters perceive her differently as a girl, which can lead to new storylines and conflicts.
One common theme is mystery. Ciel's own past and the secrets of the Phantomhive family often play a big part. Another theme could be revenge, as Ciel is on a quest for vengeance in the original story. And there's also the theme of loyalty, like the loyalty of Sebastian to Ciel which might be further explored or twisted in fanfiction.
Power dynamics is also a big theme. Sebastian is a powerful demon and Ciel is a young earl. The way they interact with each other in terms of who has the upper hand, and how that changes over time is often explored. For instance, in some fanfics, Ciel tries to gain more power over Sebastian, or Sebastian uses his power to protect Ciel in unexpected ways.
One common theme is the exploration of gender roles. Since Ciel is male in the original but is female in these fanfictions, it often delves into how different her experiences would be in the Victorian - era setting of the story. For example, how she might face different social expectations compared to her male counterpart.