Ben 110 can be developed by giving him new challenges related to the Highbreed. For example, he could face a Highbreed villain who has a power that nullifies Ben's alien forms. This would force him to rely on his human intelligence and resourcefulness. He could also develop his character by learning about the Highbreed's language and communication methods, which would show his adaptability.
One idea could be exploring Ben's new abilities as Ben 110 when dealing with the Highbreed. Maybe he discovers a unique power that can temporarily transform Highbreed into a more peaceful form. Another could be a story where Ben 110 has to team up with a group of Highbreed rebels against the tyrannical Highbreed leaders. It could also involve Ben 110 traveling to the Highbreed homeworld and learning about their culture and how to better co - exist with them.
Ben Tennyson himself is often very popular in Highbreed fanfics. He's the main character of the Ben 10 series, so it's natural that he plays a major role. Writers like to explore his interactions with the Highbreed, whether it's in battle or in attempts at diplomacy.
Well, it could be about Ben getting an unexpected Highbreed transformation. Maybe he's on a mission and somehow gets exposed to some strange Highbreed energy. Then he has to deal with new powers and also the fact that he looks like a Highbreed, which might make his friends and enemies view him differently.
A plot could involve a group of young Highbreed who are curious about Earth and its cultures, and they secretly befriend Ben. This would lead to a series of adventures where they have to hide their friendship from the more traditional and hostile Highbreed. They could learn a lot from each other, and Ben could teach them about the value of diversity and cooperation.
It could be an evil Highbreed scientist. This scientist might be obsessed with creating a new breed of Highbreeds that combines the power of the Omnitrix with their own genetic superiority. He sees Ben as the perfect test subject for his experiments and will stop at nothing to achieve his goals.
One aspect of 'Ben 10 Evil Ben Fanfic' could be the exploration of the character's dark side. Evil Ben is a fascinating take on the original Ben. It might show how he would use his powers in more malevolent ways, like using the Omnitrix to intimidate or dominate others rather than protect. This could also lead to interesting storylines involving his relationships with the other characters, as they would have to either oppose him or be corrupted by his influence.
A 'Ben loves Gwen' fanfic could explore a different side of their relationship. It might show a more romantic aspect compared to the normal sibling - like dynamic in the show. Maybe it could be set in an alternate universe where they're not related and the feelings develop naturally.
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.