Bistan from Rogue One is an underrated character. In fanfiction, you could explore his backstory more deeply. Maybe he has a connection to a planet that was once part of the Rebellion in the Star Wars Rebels era. His skills as a gunner could also be further developed, like showing how he trained or what made him such a good shot.
Melshi from Rogue One is another underrated character. A fanfiction could focus on his relationship with other soldiers in the Rebellion. He could have a story that ties him to the events in Star Wars Rebels. Maybe he once had an encounter with a character from the Rebels series that inspired him to be more involved in the fight against the Empire.
Shaak Ti. She was a powerful Jedi, but not much was explored about her in the movie. In fanfiction, you could delve into her backstory, her relationships with other Jedi, and how she might have reacted to the events of the Clone Wars and Anakin's fall. For example, she could have had a secret mission to uncover the Sith's plot that was cut short by Order 66.
Kallus from Rebels can be an interesting character to write about. He starts as an Imperial agent but then has a change of heart. Writers can explore his internal conflict, how he comes to terms with the atrocities of the Empire, and his new life as an ally to the Rebels. His transformation is full of potential for deep and engaging stories.
One underrated character is the Big Buzzy Beetle. In fanfiction, we could see a story where this character is actually a guardian of an ancient sticker relic. He's been misunderstood all this time. Also, the Shy Guys. They're quite common in the game but not really explored deeply. A fanfiction could be about a group of Shy Guys who have a secret society within the Sticker Star world and Mario stumbles upon their plans, which could be either good or bad depending on how you write it.
Commander Bly is quite underrated. In fanfiction, you could explore his relationship with Aayla Secura in more depth. Maybe show his internal struggle when Order 66 is given. Another one is Captain Rex's brother, Cody. There's a lot that could be done with his character, like showing his leadership among the clone troopers and how he dealt with the moral dilemmas during the war. And then there's Sugi, the female pirate. She has a great backstory that could be further developed in fanfiction, perhaps her adventures outside of the main Clone Wars battles.
Another plot idea might be a pre - story to the events in Rebels. It could focus on how some of the main characters in Rebels first got involved with the Rebellion. For example, a story about Hera Syndulla's early days as a pilot and how she started to gather a crew around her. It could show her first encounters with the Empire and how those experiences led her to become a key figure in the Rebellion.
One idea could be a story where a character from Star Wars Rebels gets involved in the events leading up to Rogue One. For example, Ezra Bridger could somehow cross paths with Jyn Erso and help her in her mission. Maybe he uses his Force abilities to assist in getting past some of the Empire's defenses.
The old hermit character. He was only in a few scenes but seemed to know a lot. Fanfiction could explore his past and how he came to have his knowledge. There's also the young apprentice who was often overlooked. He might have some hidden powers or a special connection to the treasures that could be delved into.
One underrated character is Baltus Van Tassel. He's Katrina's father and has a big role in the town. Fanfiction could explore his backstory, like how he came to be such an important figure in Sleepy Hollow. Maybe he had some adventures in his youth that are related to the Horseman legend. Another is the schoolmaster before Ichabod Crane. What was his experience in Sleepy Hollow? What did he know about the Horseman that he might have passed on to Ichabod? And then there's the old woman who lives on the outskirts of town. She might seem like a minor character, but she could be a seer or have some connection to the supernatural forces in Sleepy Hollow.
Rock Lee is often overlooked compared to the main characters. A fanfiction could focus on his journey to become an even greater ninja without relying on ninjutsu. Another underrated character is Shino Aburame. His unique bug - related abilities could be explored more deeply in a fanfiction, like how he might use them in different and unexpected ways.
The neighbor who was briefly shown in the movie could be an interesting character to focus on. We didn't really get to know much about him, but fanfiction could explore his story, like how he managed to survive on his own for so long. Maybe he had some unique skills or knowledge that helped him. Another could be the old man who we saw at the beginning. What was his life like before the invasion? Fanfiction could give him a more detailed backstory.