Well, in non - lemon fanfic, Sebastian is often depicted as a sophisticated, powerful demon who is bound by contract to serve Ciel. Ciel is a young, determined noble with a dark past. But in lemon fanfic which is inappropriate, it may distort their characters in improper ways for the sake of adult - themed content. So it's better to focus on their proper character traits from the original source like Sebastian's loyalty (in a non - inappropriate sense) to the contract and Ciel's intelligence and drive to seek revenge.
In non - adult 'ciel and sebastian' fanfics, Ciel is often depicted as a strong - willed and intelligent young master. He is resourceful and determined in achieving his goals. Sebastian, on the other hand, is the ever - loyal and highly capable butler. Their relationship is one of master - servant with an underlying layer of mystery and mutual dependence. Sebastian's supernatural abilities add an element of the extraordinary to their interactions, and Ciel's past traumas shape his present actions and decisions.
At first, Sebastian may be confused. Demons don't typically deal with pregnancy. However, his loyalty to Ciel would make him take on the role of a protector very seriously. He would be constantly vigilant, making sure Ciel has proper nutrition and rest. He might also start to feel a strange sense of possessiveness over Ciel and the unborn child, which is a new emotion for him as a demon. And he would have to deal with his own internal struggle as his demon nature clashes with this newfound care for Ciel and the pregnancy.
Sebastian and Ciel lemon fanfiction often explores the complex relationship between the two characters in a more intense and sometimes romantic or angsty way. These fanfictions can vary greatly in quality. Some may focus on the power dynamic between Sebastian, the demon butler, and Ciel, his young master. For example, they might depict how Ciel's vulnerability and Sebastian's unwavering loyalty (albeit with his own demonic motives) can be twisted into a more passionate connection in the fictional world created by the fanfic author.
I would recommend 'Sebastian's Temptation'. This fanfiction does an excellent job of building up the tension between the two characters. It starts with small, subtle moments of connection and gradually progresses into a more intense relationship. It also stays true to the personalities of Sebastian and Ciel from the original series. There's also 'The Forbidden Bond' which is known for its well - written dialogue and how it weaves the lemon elements into the story without making it seem out of place.
I like 'Ciel's Hidden Desires' a lot. It doesn't go too far from the original themes of the series but adds a new layer to Ciel and Sebastian's relationship. The story is well - written, and the characterizations are on point. And 'Sebastian's True Loyalties' is also a great find. It questions Sebastian's loyalty in different situations, which is really thought - provoking when it comes to his relationship with Ciel.
One great 'sebastian and ciel fanfic' is 'The Contract's Unseen Bonds'. It delves deep into the complex relationship between Sebastian and Ciel. The story shows how their bond evolves in unexpected ways, with detailed descriptions of their interactions and the emotions that come with their unique situation.