One possible theme could be love and commitment. The pregnancy would force them to reevaluate their relationship and show how deeply they care for each other. Another theme might be the impact on Narnia. As Caspian is a prince, there could be political implications of this union and the upcoming child. Also, there could be a theme of sacrifice, like Susan might have to sacrifice some of her own desires or plans for the sake of the baby and Caspian.
Perhaps a plotline where the pregnancy is unexpected and it throws Susan Caspian's life into chaos. She might have to make difficult decisions regarding her future, her relationships, and her own identity. There could also be a plotline where the father of the baby is in some sort of mystery or danger, adding more drama to the story.
I'm not sure if there are specific popular fanfictions with Susan and Prince Caspian being pregnant. It depends on the creativity of the fanfiction writers. Some might find it an interesting concept to explore the implications of such a situation on the Narnia universe, while others might not be interested in this rather unorthodox take on the characters. You may need to dig deep into fanfiction communities to find such stories.
In this fanfiction, they could go on a journey across Narnia to discover hidden secrets of the land. Since they are now married, they have a deeper connection and can communicate without words in some magical ways. Along the journey, they find ancient spells and artifacts that help them better understand the history of Narnia and how to protect it for future generations.
One possible fanfiction could start with Susan discovering she is pregnant. Caspian is overjoyed but also filled with a sense of responsibility. They start preparing a nursery in the castle, with Caspian bringing in the finest woods and fabrics. Susan spends her days knitting baby clothes, dreaming of their future child. Their friends in Narnia are excited too, and they all gather to offer their support and gifts. As the pregnancy progresses, they face some challenges, like when Susan has a difficult day of morning sickness, but Caspian is always by her side, bringing her soothing herbal teas.
A possible plot is that Susan discovers she is pregnant during a time of unrest in Narnia. Caspian is worried about how to protect her and the unborn child. They decide to go into hiding for a while in a secret part of Narnia. There, they live a simple life, and Caspian learns to be more self - sufficient, like fishing and hunting for food. As the pregnancy progresses, they form a deeper bond. Eventually, they return to the kingdom when things have calmed down, and they are welcomed with open arms as they await the birth of their child.
One common theme is adventure. Since both characters are often associated with fantastical worlds, they embark on exciting quests together in many fanfictions. Another theme is love. Whether it's a budding romance or a deep, unspoken affection, it's frequently explored.
I don't know of any specific Susan and Caspian pregnant fanfiction to recommend. It's a rather specific concept, and while there could be some out there, it may be a bit hard to find. Maybe you could start by looking at the works of well - known fanfiction writers in the Narnia fandom and see if any of them have explored this idea in their stories.
One possible plot could be that they face challenges in Narnia while Susan is pregnant. Maybe there are threats to the kingdom that they have to deal with together, all while preparing for the arrival of their child. Caspian might be extra protective of Susan, and they could rely on the help of their friends in Narnia.
A common theme is the cultural differences they might face. Since they come from different worlds in the original stories, fanfiction often explores how they bridge those gaps in their married life.
Another theme could be the integration of Susan's human world values and Caspian's Narnian ways when it comes to parenting. This can lead to interesting cultural clashes and reconciliations. And of course, the theme of love is always present, not just the love between Susan and Caspian but also their love for their baby and how it shapes their actions and decisions in the story.