One popular idea is crossovers with other popular animated shows like Teen Titans. It's exciting to see the Ben 10 characters interact with the Titans. Another idea could be a crossover with the Powerpuff Girls, imagining how the different powers and personalities would clash or cooperate. Also, crossovers with the Justice League can be really cool, as Ben 10's alien forms could bring a new dynamic to the superhero team.
One idea could be exploring an alternate universe where Ben has different alien forms with unique abilities not seen in the original series. Another could be a story focused on Ben's relationships with his friends and family in a more in - depth way, like how they react to his alien - changing powers. A third idea might be a time - travel story where Ben goes back in time and has to use his powers to fix something in the past.
One idea could be Ben Tennyson using his Omnitrix to team up with Spider - Man. Ben could transform into XLR8 to chase down villains while Spider - Man swings through the city. Another could be having Four Arms help the Hulk in a battle, combining their brute strength. And perhaps Heatblast could join forces with the Human Torch to fight a fire - based villain.
One idea could be to have Ben Tennyson end up in the Young Justice universe by accident. Maybe his Omnitrix malfunctions during a fight and transports him there. He could then team up with the Young Justice heroes to fight a common enemy like the Light or some new villain that's a threat to both universes.
One idea could be that Ben Tennyson, while on a mission in another dimension, accidentally lands in the X - Men's universe. His Omnitrix starts acting strangely due to the different energy signatures there. The X - Men initially see him as a threat but then realize he could be an ally in fighting a common enemy, like a powerful mutant - alien hybrid that is causing chaos. Ben could transform into some of his alien forms to help the X - Men in battles, and there could be interesting interactions between the different characters, like Gwen and Rogue comparing their powers.
One popular idea is a crossover with other visual novels. For example, combining the characters from DDLC with those from a more light - hearted VN like Nekopara. The contrast between the cute catgirls and the sometimes darker themes of DDLC can create interesting storylines.
Some great 'Spongebob crossover fanfic' ideas include a crossover with 'Scooby - Doo'. The gang could visit Bikini Bottom to solve a mystery that involves Spongebob's pineapple house. A crossover with 'Digimon' is also possible. Spongebob and the gang could enter the digital world and befriend some Digimon. And a crossover with 'Powerpuff Girls' would be cool. The Powerpuff Girls could fly to Bikini Bottom to help Spongebob fight some new underwater villain.
One popular idea could be a crossover between 'House' and 'Sherlock'. Imagine House and Sherlock Holmes trying to solve a case together, with their different diagnostic methods clashing and then merging. Another could be a crossover with 'Scrubs', where the comical hospital setting of Scrubs meets the more serious medical drama of House. Maybe JD from Scrubs could learn a lot from House's unorthodox ways.
One popular idea could be a crossover with other superhero shows like 'Teen Titans'. The Miraculous characters could team up with the Titans to fight a common enemy. Maybe Hawk Moth creates a powerful villain that requires both groups' powers to defeat.
A really interesting fma crossover fanfic idea might be with the world of Fullmetal Alchemist and the Lord of the Rings. Imagine the Elric brothers in Middle - earth, facing the challenges there. They could use their alchemy skills in a world filled with magic, elves, and orcs. It would be a very unique combination as the concepts of alchemy and the magic in Middle - earth are quite different.
Well, a Halo crossover fanfic could involve Halo and the Alien franchise. Picture the Covenant or Spartans dealing with the Xenomorphs. It would be really intense. Also, a Halo and Doom crossover could be interesting. The Doom Slayer and a Spartan teaming up to take on demons and the Covenant would make for an action - packed story. And a Halo and Fallout crossover, where the post - apocalyptic world of Fallout meets the high - tech world of Halo, could also be a great concept.