One idea could be exploring a different backstory for Alina. Maybe she was born with her powers but had to hide them in a more complex way than in the original story. Another could be a fanfic where Mal and Alina's relationship develops in a parallel universe where the Darkling never existed. This would change the dynamic of their love and how they face the challenges in Ravka.
One idea could be that as a girl, Shadow has to face different challenges in a male - dominated Sonic world. Maybe she has to prove herself constantly to be accepted as a strong fighter.
One idea could be a story where Naruto discovers a new, hidden aspect of his shadow powers that allows him to communicate with the shadows of the past ninjas. He could learn ancient techniques from them and use this knowledge to defeat a powerful new enemy.
One idea could be that Silver and Shadow are forced to team up to stop a new, powerful enemy that threatens their world. They start off distrusting each other but as they face challenges together, they begin to understand and respect one another.
Well, a great plot could be centered around a mystery. Let's say there are strange occurrences in their world that seem to be related to Bakugan Shadow's past. Mylene becomes determined to solve this mystery. As they dig deeper, they uncover secrets that not only change their understanding of Bakugan Shadow but also put them in danger. They might have to face off against an ancient enemy who is trying to keep these secrets buried. Mylene uses her intelligence and courage, while Bakugan Shadow uses its strength and special powers to overcome the obstacles in their path.
One plot idea could be that Rose discovers Cid's true power in a moment of crisis. For example, when facing a powerful enemy that the Shadow Garden can't easily defeat, Cid reveals his real capabilities to save Rose and the others. Another idea is a love triangle where Rose has feelings for Cid, but Cid is so focused on his shadowy plans that he doesn't notice at first, while another character also vies for Rose's attention.
Another plot idea could involve a new character who has the power to manipulate shadows during the war. This character could initially be an enemy but then realizes the true nature of the conflict and switches sides. They could use their shadow powers to help the Fairy Tail guild in unexpected ways, like creating shadow portals to quickly move around the battlefield.
One idea could be the Shadow Hunter having to face a powerful ancient beast in the wild. Maybe it's a creature long forgotten, and the hunter must use all their skills and knowledge passed down through generations to defeat it.
A great plot idea for a Star Wars Shadow of the Empire fanfic could be to expand on the relationship between Dash Rendar and Leia Organa. Maybe there are some untold adventures they had together that didn't make it into the official story. Another option is to explore the criminal underworld more deeply. Show how different gangs and syndicates operate during this time and how they are affected by the larger conflict between the Empire and the Rebellion. You could also create a story about a lost Jedi artifact that is discovered during the events of Shadow of the Empire and how different characters are drawn to it for different reasons, whether it's for power, knowledge, or to keep it out of the wrong hands.
Another interesting concept is to create an alternate universe where the power dynamics are completely different. Maybe the shadow organization is the ruling power, and the story focuses on how the world adapts to that. It could also involve the main character having to deal with different challenges in this new setup.
One idea could be exploring Karou's life before the events of the book. Maybe show her training with Brimstone in more detail, her relationships with the other chimaera, and how she first started to question her place in their world.