She could also be a key figure in the political intrigue of Camelot. As Arthur's sister, she has a certain status. There might be those who try to use her to get to Arthur or undermine his rule. So she has to navigate the dangerous world of court politics, using her wits and charm to outwit her enemies and protect Arthur and Camelot.
She could be very brave. Growing up in Arthur's shadow, she might feel the need to prove herself just as worthy. So when faced with danger, she doesn't cower but stands up and fights, whether it's against a magical beast or a political enemy.
There are also fanfictions where the OC is a commoner with a hidden noble lineage. In this story, as they interact with Arthur, they gradually discover their true heritage. This kind of plot often involves a lot of character development for both the OC and Arthur as they navigate through their new relationship while dealing with the court politics and the threat of Morgana.
Saber from Fate/Stay Night would be an obvious choice. Since she is also related to the Arthurian legend, there could be a lot of interesting interactions between them. They could compare their experiences as king, or even fight side by side against a common enemy.
One interesting plot could be Hisoka's sister getting involved in the Hunter Exam. She might use her unique skills, perhaps some that are similar to Hisoka's but with her own twist, to navigate through the challenges. For example, she could have a special ability to read opponents' intentions like Hisoka, but she uses it in a more empathetic way to avoid fights when possible.
One interesting plot could be that Gaara's little sister has a special power that she has to keep hidden from the village at first. This creates a lot of mystery and tension as she tries to navigate her life without being discovered.
One interesting plot could be her going on adventures with Natsu and his friends. She might have unique magical abilities that help the group in their quests.
One great Arthur Pendragon hurt fanfiction is 'The Wounded King' which delves into his emotional turmoil after a major battle. It shows his struggle to regain his strength both physically and mentally.
Well, in such a fanfiction, they could team up against a common enemy. Maybe an ancient dark force that has been awakened in both their times. Their combined knowledge of magic from different eras would be a great asset.
A fanfiction that stands out is 'Arthur and Merlin: A Different Path'. This one takes a different turn from the original storyline. It imagines a world where Arthur discovers Merlin's magic much earlier. This changes the whole dynamic between them, and they face different challenges together. There is also 'The Adventures of Merlin and Arthur in the Enchanted Forest'. It's full of exciting quests and the development of their friendship.
Arthur Pendragon might fall in love with a noblewoman from a neighboring kingdom. Their kingdoms have a long - standing alliance. They meet at a grand ball held to strengthen the bond between the two lands. Arthur is immediately drawn to her grace and intelligence. They start writing letters to each other when she returns to her kingdom. Their love blossoms through these letters, but political intrigues and power - hungry lords try to break their relationship apart as they fear the united front of the two kingdoms through their love.