Love and loyalty are common themes. Often, these fanfics explore how Lizzy's love for Ciel endures despite his dark secrets. Another theme is growth. Ciel may grow as a person because of Lizzy's influence, and vice versa.
Adventure could also be a theme. Writers might put Ciel and Lizzy in various adventurous situations where they have to rely on each other and their relationship deepens as a result. For example, they could be on a quest together to solve a mystery or defeat an enemy. This not only adds excitement to the story but also gives more depth to their relationship.
In some ciel x lizzy fanfictions, there is a theme of self - discovery. As they interact more, they learn more about themselves. Ciel might discover a softer side of himself because of Lizzy, and Lizzy might find more strength in herself. Also, the theme of loyalty often comes up, as they prove their loyalty to each other in different situations in the stories.
The plot also matters. A fanfic could be about their relationship evolving during a dangerous mystery they have to solve together. This gives the story an exciting backdrop and allows for interesting interactions between the two characters. It should have a good balance between their personal relationship growth and the external events happening around them.
Ciel would likely become more protective. He has always been in a dangerous world, and now with a baby on the way, he'll do whatever it takes to safeguard his family. Lizzy, she might become more nurturing. She was already a strong character, but motherhood could bring out a softer, more patient side of her.
There's a 'ciel lizzy fanfic' called 'A Dance in the Moonlight'. In this fic, the author focuses on their unspoken feelings. It's a rather sweet and tender story, where every interaction between Ciel and Lizzy is filled with unexpressed emotions that gradually unfold as the story progresses. It's really a great read for fans of the pairing.
A fanfic might explore their relationship in a different time period. For example, what if they were children again? They could have innocent playdates that gradually reveal their deep - seated feelings for each other. Ciel might be less guarded around young Lizzy, and she could bring out his softer side.
A fanfic could show a moment where Ciel is at his most vulnerable, and Lizzy is the only one there to comfort him. Perhaps after a particularly difficult encounter with a foe, Lizzy finds Ciel in his study, and she simply holds him without saying a word, which means a great deal to Ciel.
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 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.