Perhaps in the fanfiction, there's a love triangle. Prince Caspian is betrothed to someone else, but he has strong feelings for Susan. Susan also has feelings for him but doesn't want to cause trouble. They have to navigate their emotions while also dealing with political unrest in Narnia.
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 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 Peter gets lost in the forest of Narnia on his own during a quest and has to rely on his wits and some unexpected help from a minor character in the Prince Caspian story to find his way back to the main group. Another could be a time - travel twist where Peter is sent back to a crucial moment in Prince Caspian's past and has to figure out how to change things without disrupting the future of Narnia too much. And perhaps a story where Peter and Prince Caspian have a misunderstanding that leads to a mini - adventure to resolve their differences and strengthen their bond.
One idea could be that Lucy discovers a hidden magical ability that helps Prince Caspian in a crucial battle. For example, she might be able to communicate with the spirits of the forest in a way that no one else can, and these spirits provide strategic advice to defeat an enemy. Another plot could involve Lucy getting lost in a mysterious part of Narnia and Prince Caspian embarking on a quest to find her, during which they both learn more about each other's pasts and grow closer.
One idea could be a story where Peter and Caspian have to go on a secret mission together to find a lost magical artifact that can save Narnia from a new threat. They start off not getting along but gradually learn to respect each other's skills.
One possibility could be that the story focuses on how they adjust to parenthood in the magical world. They might face challenges from those who oppose their union or from the powers that be in Narnia. The baby could also have some special powers or a great destiny.
One plot idea could be that Fem Harry Potter somehow gets transported to the world of Narnia during the time of Prince Caspian. She could use her magic skills, learned from Hogwarts, to help Caspian in his battles. For example, she might use spells like Protego to shield his army from enemy attacks.
There is a fanfiction where Susan is a healer and Caspian is injured in battle. Susan takes care of him and during his recovery, they start to realize their feelings for each other. It's a slow - burn story that really delves into their personalities and how they complement each other.
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.
A plot could involve Caspian being cursed and Susan being the only one who can break it. She has to go on a quest to find a magical object. Caspian, in his cursed state, can't directly help but his spirit encourages her. Along the way, Susan discovers her own hidden powers and in the end, she breaks the curse and they confess their love for each other.
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.