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 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.
It could be a jealous sorcerer who was once in line for the throne of Narnia. Now that Prince Caspian has married Susan, he sees his chance of power slipping away. So he tries to create chaos and turn the Narnian people against the new couple.
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.
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.
One idea could be that Susan returns to Narnia during a time of great peril, and she and Prince Caspian have to team up to defeat a new, powerful enemy. They might discover hidden powers within themselves along the way.
One idea could be that Susan returns to Narnia in a time of great need, and she and Prince Caspian have to work together to defeat a new, powerful enemy. Maybe they discover an ancient magic that only they can unlock through their combined efforts.
One great source could be fanfiction.net. There are often many different takes on Caspian and Susan's relationship in fanfiction on that platform. You can search using the tags related to their names and'married' to find relevant stories.
Well, Susan is often seen as a bit more worldly compared to Caspian in some fanfictions. Since she has been to Narnia before and has some knowledge of different cultures and magic there. Caspian, being from Narnia but in a different era, is in awe of her in a way. Their relationship can be complex. It could be a relationship where they both learn from each other. Susan can teach Caspian about the 'old ways' and Caspian can show Susan the new Narnia he is building. This kind of interaction makes for really engaging fanfiction.
I'm not sure specifically if there is a fanfiction with Susan and Caspian where there is a pregnancy. There are a vast number of fanfictions out there, and it would depend on the creativity and direction of different authors. Some fanfictions might focus on adventure and relationship building between the two characters without including such a plot element, while others might explore more complex storylines that could involve pregnancy.
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.