One idea could be exploring the backstories of the characters in the 'hill of swords' world. Maybe a character has a hidden past related to a lost civilization in that realm.
A plot about a character who is an outcast in the 'hill of swords' society and their journey to gain acceptance and prove their worth. They might have to overcome prejudice and difficult trials along the way.
Another plot idea could involve a quest to find a powerful artifact on the hill of swords. The characters would face various challenges and enemies during their search.
Another plot could involve a prophecy that states only the one who can balance the power of the two swords can bring peace to the land. The protagonist is chosen to do this but faces many temptations and obstacles along the way, as there are those who want to use the swords for their own evil purposes.
One plot idea could be Theo and Nell exploring the secrets of Hill House together that were previously unknown. Maybe they find a hidden room that holds the key to understanding the house's malevolence.
A cool Silent Hill fanfiction idea is to focus on the psychological aspect more deeply. Maybe write about a psychologist who visits Silent Hill to study the mental states of the people there. He gets trapped and starts to experience hallucinations related to his own past traumas. Also, a fanfiction where the monsters in Silent Hill are given a chance at redemption. What if they could be cured of their 'evil'? It would be an interesting take on the usual horror theme.
Another plot could revolve around the characters having premonitions of the events that are going to occur in the quarry. They then have to decide whether to trust these visions and how to act upon them. This could add a whole new layer of suspense and mystery to the story.
One idea could be a time - travel plot. The Backyardigans accidentally find a magical object in the backyard that sends them to different eras in history. They could have to work together to find their way back home while also learning about the different time periods. For example, they might end up in the prehistoric era and have to deal with dinosaurs.
One idea could be a story where one of the dalmatian puppies gets lost during a family outing and has to find its way back home, facing various challenges along the way.
One idea could be exploring the backstory of a minor character in the Bioshock universe. For example, a splicer's journey before they became spliced. It could show how they were once an ordinary citizen of Rapture and what led them to make the fateful decision to use ADAM. Another plot could focus on an alternate timeline where the protagonist makes different choices. Maybe they side with the wrong faction and have to deal with the consequences. A third idea is a story centered around a new type of plasmid that has unexpected effects on the user and how it impacts the power dynamics in Rapture.
Another plot could involve the creation of a female monster. In the original, Victor Frankenstein was hesitant to create a female. A fanfic could explore what would happen if he did. Maybe the two monsters would have a complex relationship, and together they would try to find a place in the world that would accept them.
One idea could be that Batman and Wonder Woman team up to stop an ancient, otherworldly threat that's beyond the capabilities of the Justice League alone. They have to travel to different dimensions and rely on each other's unique skills.
A heatwaves fanfic could center around a young couple. The heatwave makes their living situation difficult, like their apartment has no air conditioning. They have to find creative ways to cool off and in the process, their relationship deepens. They could also get involved in community efforts to help those more affected by the heatwave, such as the elderly or the homeless.