One key element is the relationship between Ciel and Elizabeth. Their complex dynamic, with Ciel's often - brooding nature and Elizabeth's more upbeat and innocent personality, is often explored. Another element is the Victorian setting which provides a rich backdrop for the stories.
Well, 'Ciel and Elizabeth's Secret Adventure' is also a great one. It takes the two characters on an unexpected journey where they discover new things about each other and their own capabilities. The story has a good balance of action and romance.
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.
The relationship development is very interesting. Since Ciel has his own dark past and Elizabeth has her own expectations of marriage, seeing how they come together and make it work in fanfiction can be really engaging.
You can try Archive of Our Own (AO3). It has a vast collection of fanfictions, including many about Ciel and Elizabeth. Just use the search function and type in their names to find relevant stories.
Well, 'Ciel and Elizabeth: Hidden Feelings' is quite interesting. It starts with Elizabeth realizing some hidden feelings she has for Ciel that she hadn't been fully aware of before. This fanfiction then takes the readers on a journey of self - discovery for Elizabeth and how it impacts her relationship with Ciel.
One great place to find Ciel Phantomhive and Elizabeth fanfiction is Archive of Our Own (AO3). It has a large collection of works with various themes and interpretations. You can also check Fanfiction.net, which has been around for a long time and has a good number of such fanfictions as well.
One popular 'ciel and elizabeth married fanfiction' is 'A Married Life for Ciel and Elizabeth' on FanFiction.net. It beautifully portrays their married life with a lot of sweet moments between them. The author does a great job of showing how they adjust to living together and facing various challenges as a married couple.
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.
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.