One possible aspect of 'ciel x sebastian jealous fanfic' could be the exploration of complex emotions. In many such fanfics, the jealousy might stem from the unique relationship between Ciel and Sebastian. For example, if there's a new character introduced, Ciel might feel jealous of the attention Sebastian gives to that character. It can add an interesting layer to their relationship which is already full of mystery and power dynamics.
One aspect could be the complex relationship between Sebastian and Ciel in the fanfic. Sebastian's jealousy might stem from his possessive nature over Ciel. He is Ciel's butler but also has a deeper, perhaps unspoken bond. This jealousy could add a new layer of tension to their interactions, for example, when other characters get too close to Ciel. It might lead to some interesting plot developments like Sebastian becoming more protective or overbearing in a way that both confounds and endears him to Ciel.
The 'sebastian x ciel modern fanfic' often explores different themes. For example, it could focus on how they adapt to modern society's values. Sebastian, with his old - world values, might clash with modern ideas, while Ciel has to navigate the fast - paced modern world. The fanfic might also play with the idea of their relationship being discovered in a more open - minded but still judgmental modern society.
One popular trope is the 'fish out of water' for Sebastian. As he is from a different era or world in a sense, seeing him adjust to modern technology like smartphones and the internet can be really interesting. For example, he might be confused by social media but quickly learn to use it to protect Ciel.
I really like 'The Crimson Contract'. It takes their relationship in a unique direction. It has a great plot that isn't just about the romantic aspect but also about the power dynamics between Sebastian and Ciel. It's full of interesting twists and turns.
One popular trope is the 'Forbidden Love' aspect. Since Sebastian is a demon and Ciel is a human, their relationship can be seen as something that goes against the natural order. Another is the 'Power Struggle' trope. Ciel may try to assert his authority over Sebastian, but Sebastian's demonic nature gives him an edge in certain situations. 'Soul Bond' is also common. Given their contract and the connection it implies, fanfictions often explore the deeper spiritual and emotional bond that might develop between them.
A common theme is possessiveness. Since Ciel and Sebastian have a rather special bond, any threat to that bond can trigger possessiveness which is often expressed as jealousy. Another theme could be the fear of loss. Ciel, having lost so much already, might be terrified of losing Sebastian to someone else, and this fear can manifest as jealousy.
I really liked 'A Moment of Solace'. In this fanfic, Ciel is injured and Sebastian takes care of him. It's full of tender moments that really highlight the unique bond between them. There are some really great emotional exchanges that make it a top pick for this genre.
One common theme is the adaptation of their traditional power dynamic into a modern context. For example, Sebastian's loyalty to Ciel might be shown in a corporate or academic setting. Another theme is the exploration of their relationship in a more open and accepting modern society. It could involve Ciel coming to terms with his feelings for Sebastian more easily than in the original Victorian - era - based story.
In these fanfics, a recurring theme is the power dynamic. With Sebastian being jealous, it can either strengthen or weaken the power he has over Ciel. If he becomes over - protective due to jealousy, Ciel might gain some power in the relationship as Sebastian's actions are more driven by emotion. Another theme is the idea of loyalty. Sebastian's jealousy could be seen as an extreme form of loyalty, not wanting anyone else to have what he considers his (in relation to Ciel). And of course, the theme of love, in a very complex and often unspoken way, is also quite common as the jealousy is often a sign of deeper feelings.