There are some really cool 'Ben 10 Alien Force Fanfiction' out there. 'The Mutant Invasion' is a story where mutants from another dimension invade Earth and Ben has to use his alien forms in unique combinations to fight them. 'Gwen's New Powers' is another interesting one. It shows Gwen developing some unexpected powers and how she and Ben deal with that. Also, 'Kevin's Redemption' is a story that focuses on Kevin trying to make up for his past mistakes.
One possible fanfiction could be about Ben and Kai going on a new adventure in the Omniverse. Maybe they discover a new alien species that is causing chaos in a far - flung galaxy. Ben uses his Omnitrix to transform into different aliens to try and stop the threat, while Kai uses her martial arts skills to fight alongside him.
One possible plot could be that Rook and Ben go on an adventure to a new planet in the Ben 10 Omniverse. They encounter a strange alien species that has a unique power. Ben tries to use his Omnitrix to transform into an appropriate alien to deal with the situation, but there are some glitches. Rook, with his Plumber skills, helps Ben figure out what's wrong and together they overcome the challenges and make new friends among the aliens.
I haven't actually read this specific fanfic, but generally in a 'Ben x Esther' fanfic in the Ben 10 Omniverse setting, it might explore their relationship in different ways. It could involve adventures where they team up, and their characters' growth while dealing with various threats in the Omniverse. Maybe it also delves into how their different personalities interact and complement each other.
Well, in a fanfiction, they could be on a mission to save a planet that is on the verge of destruction. Ben uses his alien powers to hold off the immediate threats, like asteroids or attacking creatures, while Kai tries to find the root cause of the planet's problems, which could be some sort of evil technology or a corrupt leader.
One great Ben x Kevin fanfiction could be about their adventures in a parallel dimension. In this story, they might face new aliens and challenges that test their friendship even more. Maybe they find a powerful alien artifact that only works when they combine their unique abilities, leading to a deeper understanding of each other.
One common theme is power combination. Writers often explore how the powers from Naruto, like chakra - based jutsus, can be combined with the alien powers in Ben 10 Alien Force.
Well, it might be about how time heals the wounds or problems within the Ben 10 Alien Force universe. It could be that characters who had conflicts in the past are brought together by some time - related event. For example, perhaps an old villain returns but through the passage of time, Ben and his team have grown stronger and more united, and they use this new - found strength to face the threat. They might also discover something about the origin of their powers or the history of the aliens that is related to time.
Well, if Ben was kidnapped in fanfiction, his friends would probably start a huge rescue mission. Gwen would use her magic and Kevin his powers to track him down. They'd face all sorts of challenges along the way, like bad guys trying to stop them or traps set by the kidnappers.