One idea could be exploring what would happen if the siblings had different powers. For example, if Luther could control time instead of having super strength. It would change the dynamics of their relationships and how they handle missions.
Another plot could be set in an alternate universe where the Umbrella Academy was never formed. Each member has to find their own way in the world, but then a new threat emerges that only they can stop together. This would involve a lot of character development as they come together from different paths.
You could also write a fan fiction about a time when the siblings were kids and they had to deal with a local villain in their neighborhood before they became world - savers. It would show their early powers and how they learned to work as a team, with a more light - hearted and small - scale adventure.
For Umbrella Academy fan fiction, you could write about a scenario where a new sibling is discovered. This new character could have a power that either complements or clashes with the existing siblings' powers. They would have to integrate into the group and deal with the family dynamics. Another plot could be that the Umbrella Academy is transported to a different era, like the 1920s, and they have to adapt to the new time period while also trying to find a way back to their own time. And a third idea is a story where they have to face a threat that is specifically targeting their weaknesses as a group, forcing them to confront and overcome their personal issues.
One idea could be exploring what would happen if a new member joined the Umbrella Academy. Maybe a time - traveling superhero from the future who has knowledge of a great threat coming. Another could be a story where the members lose their powers and have to rely on their wits and teamwork in a completely different way. For example, dealing with a powerful enemy who can nullify powers.
A great plot could be that The Handler gets amnesia. Losing her memory, she has to rely on the kindness of the Umbrella Academy members she once opposed. This forces her to see them in a new light and also makes her question her own actions. It could lead to a journey of self - discovery for her within the world of the fanfiction.
Perhaps the fanfiction could be about a baby that is the result of a time - travel accident within the Umbrella Academy world. The baby has a mix of powers from different eras and the academy members have to figure out how to deal with this unique situation. They might have to teach the baby how to control its powers while also protecting it from those who fear its abilities.
A possible plot idea is that Klaus discovers that his ghost - seeing ability is not just a random power, but part of a much larger, supernatural plan. The ghosts he sees are actually messengers from a different dimension, and they are trying to guide him to save both his world and theirs. Also, the fanfiction could explore a plot where Klaus' relationship with a particular ghost deepens into a strange friendship. This ghost has the ability to enter the dreams of the other Umbrella Academy members, and Klaus has to use this to his advantage to solve a mystery within the academy. Or, there could be a story where the ghosts start to disappear one by one, and Klaus has to race against time to find out what is causing it and stop it before he loses his connection to the spirit world completely.
Another plot could involve Five getting sick due to some side - effect of his powers overusing them in a short period. As he gets sicker, he starts to lose his memories of different timelines he has visited. The story could then focus on his journey to regain those memories with the help of his siblings.
One idea could be creating an OC who has the power to manipulate time in a different way than Five. For example, they can freeze time for specific objects or people while the rest of the world continues as normal. This would add a new dynamic to the Umbrella Academy's adventures and interactions with the timeline.
Another great crossover could be with 'The Boys'. In this scenario, the Umbrella Academy would be thrown into the world of corrupt superheroes. They would have to navigate the complex politics and power plays while also trying to stay true to their own values and not get caught up in the dark side of superhero - ism.
Klaus is a very popular character to focus on. His ability to communicate with the dead makes for some really interesting and spooky storylines. You can explore his relationship with his powers and how it affects his mental state. Five is also a fan favorite. His time - traveling abilities and his no - nonsense attitude provide a lot of material for fan fiction. And of course, Vanya. Her journey of self - discovery with her powers can be delved into deeply in fan fiction.
One idea could be a story where the Mandalorian has to team up with an old enemy to fight a new, greater threat. Maybe a powerful Sith Lord emerges and they have to put aside their differences.