A popular type of Ben x Kevin fanfiction is the 'what - if' scenarios. For example, what if Kevin had been the one to get the Omnitrix instead of Ben? This would completely change the dynamic of their relationship. They could start as rivals with the power, but gradually realize they need each other to face the bigger threats in the universe.
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.
The relationship between Ben and Kevin has room for growth. In fanfiction, they can develop feelings for each other that are more than just friendship. This adds a new layer of depth to their interactions. Writers can show how they deal with these new emotions while still being heroes and facing the threats in the Omniverse. There are also the power dynamics between them. Ben has the Omnitrix, but Kevin has his own unique powers, and how they combine or clash in different situations can make for exciting reading.
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.
The main characters are obviously Ben and Kai. Ben is the wielder of the Omnitrix, which gives him the power to transform into various alien forms. Kai is a strong - willed and adventurous character who often gets involved in Ben's escapades.
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.
Another plot might involve Ben and Kai getting accidentally transported to a parallel dimension where things are very different. They have to find a way back home while also dealing with the strange new versions of their friends and foes. Along the way, they discover new things about each other and their feelings start to change in this unfamiliar setting.
Maybe in the fanfiction, Esther gets into trouble while exploring a dangerous part of the Omniverse. Ben discovers her plight and decides to rescue her. As he does, they find themselves in a situation where they are trapped and have to rely on each other to escape. During this time, they share their hopes, dreams, and fears. Ben realizes that Esther is more than just a friend, and Esther sees Ben in a new light. Their relationship blossoms from there, with them having adventures together and supporting each other in the Omniverse.
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.
Perhaps a story where an old enemy of Ben's targets Rook to get to Ben. Ben feels guilty and protective. They go on the run, hiding in different places across the galaxy. Along the way, they meet some interesting characters who help them. In the end, they face the enemy together, with Ben using his Omnitrix and Rook using his upgraded Proto - Tool to defeat the bad guy.
One popular plot twist is when Ben and Gwen end up in a different dimension where their roles are reversed. So, Gwen has something like the Omnitrix and Ben has to rely on his wits and basic combat skills without alien forms. This forces them to adapt in new ways and understand each other's struggles better.
One possible plot could be that Esther gets caught up in an alien conspiracy in the Omniverse. Ben, being the hero, steps in to save her. As they work together to uncover the truth behind the conspiracy, they start to fall for each other.