You could also write a fanfiction focused on the relationships between different dolls. Maybe there's a secret friendship or a rivalry that wasn't fully explored in the original, and you can expand on that. For instance, two dolls from different floors forming an unlikely alliance.
Another concept could be a 'what if' scenario. Like what if a doll and their master had a complete role reversal? This would change the whole dynamic of the story and could lead to some really unique plotlines.
One interesting concept could be exploring new shadow - based jutsu that the characters develop. For example, a fanfiction might introduce a jutsu where a character can create multiple shadow clones that are made entirely of shadows, with different properties from the regular shadow clones. This could add a new layer of strategy in battles.
The dark shadows in some Harry Potter fanfiction might represent the hidden, dark side of Hogwarts itself. There could be secret passages and rooms that are filled with 'dark shadows' both literally and metaphorically. These areas might hold secrets about the founders or dark magic that was once practiced within the school walls. It could add a sense of mystery and danger to the familiar Hogwarts setting.
A great plot for House of Dark Shadows fanfiction could be to create a parallel universe where the events of the story took a different turn. Maybe the main villain had a change of heart early on, and how that would affect the rest of the characters and the overall story. Also, you could write about a character who discovers a hidden power within the house that was previously unknown, and they have to figure out how to use it or keep it from falling into the wrong hands. Or, write a story from the perspective of the house itself, as if it were a sentient being with its own motives.
Perhaps the fanfic explores the relationship between the host and the symbiote in a new way. For example, how they communicate and influence each other's emotions.
One interesting concept could be crossovers with different Disney universes. For example, having characters from 'Frozen' interact with the regular House of Mouse crew. It creates new and unexpected storylines.
One interesting concept could be the character's knowledge from their previous life affecting their actions in the House of the Dragon world. For example, they might use modern strategic thinking to navigate the complex political situations in the story.
In 'house divided star wars fanfiction', a cool concept might be the division of planets. Some planets could be split between different factions, leading to unique cultural and political situations. For example, a planet that was once united now has one half siding with the Sith and the other with the Jedi, causing chaos and new storylines.
Another aspect is the exploration of different timelines. In 'The Owl House' time travel fanfiction, we might see how the world would be if certain events happened differently. Maybe Luz could go back in time and prevent some of the chaos caused by Belos earlier, which would lead to a completely different Boiling Isles.
In some fanfictions, house unity might be centered around a new magical sport or event that requires the combined skills of all the houses. The unique traits of each house, like Gryffindor's courage, Hufflepuff's loyalty, Ravenclaw's wisdom and Slytherin's cunning, are all needed to succeed in this activity. This not only promotes unity but also a new level of understanding between the houses.
One interesting concept is the idea of house - elves gaining more rights. In some fanfictions, they form unions or rebel against the traditional wizarding hierarchy. Another concept could be a house - elf having magical abilities that are far beyond what is shown in the original books, like being able to perform extremely powerful spells. Also, there are fanfictions where a house - elf forms a deep friendship with a wizard or witch outside of their serving duties, which is quite different from the normal master - servant relationship in the original story.