Definitely Ben, since he is at the center of the whole Omniverse concept. His character growth throughout the series gives a lot to work with. However, don't overlook characters like Rook. He has an interesting backstory and his loyalty to Ben can be explored in fanfiction. Also, Vilgax is a classic villain that can add a lot of drama and action to a story.
Ben is an obvious choice as he is the main character. His different alien forms offer a lot of possibilities for storylines. Gwen is also great as she has her own powers and a complex relationship with Ben. And of course, Kevin, with his unique abilities and his friendship - turned - rivalry - turned - friendship again with Ben.
In 'ben 10 omniverse fanfiction', Ben is a must - focus character, but other characters like Azmuth can be really interesting. He is the creator of the Omnitrix and his knowledge and motives can be delved into. Then there's Eon, a powerful and mysterious character. A fanfiction exploring his origin and his connection to Ben could be really engaging. Also, characters like the Plumbers can be used to create a more complex world - building in the fanfiction.
Look to Chapter 58 for the clearest answer. It begins with Facing Jiang Yan's triple barrage of questions, Jiang Li's only response..., keeps building through After a long while, she yawned indifferently and said, "I didn't pick up..., and lands on By ten o'clock, Jiang Yan was still wandering.
The best chapter pointer here is Chapter 99, "Dear Sister, Save Me!!!". It opens with Seeing the man approach, one of the individuals with a long scar across... and closes on Just as she was considering whether to practice a set of boxing, her phone....
Look to Chapter 118 for the clearest answer. It begins with At 8 in the morning, several guests appeared on time next to the..., keeps building through Seeing the five individuals walking together in unison, Director Sun was..., and lands on Hearing this, both Jiang Yan and Shu Yan started to.
If you want the clearest chapter reference, go to Chapter 95. Early on, Hearing others praise her daughter, Aunt Lin was smiling so wide she...; later, the chapter leans on Lingling really is a good child..
A practical answer is Chapter 70, because it turns the idea into a concrete scene. The chapter opens with So, under the curious gazes of everyone, Jiang Yan strutted up with his..., adds pressure through Back at the airport, He Yun hadn't even greeted her., and ends on He Yun was also surprised as.
Look to Chapter 91 for the clearest answer. It begins with When Jiang Li saw that he had been assigned a harrow, Qi Tianyu felt his..., keeps building through My tool couldn't possibly be a shovel, could it?" Director Sun chuckled..., and lands on Hahaha, Young Master, what the heck are you.
Chapter 54 is the strongest chapter-level answer because it starts from Five minutes later, the people of Chixia Village, who had received the... and follows through on She was also polite and friendly, and to top it off, she was good-looking,....
The best chapter pointer here is Chapter 112, "The Strange "Team Spirit" Appears". It opens with These five people are supposed to be at odds. and closes on [Hahahaha why is the Princess starting to look disappointed?] [Help, even....
A practical answer is Chapter 85, because it turns the idea into a concrete scene. The chapter opens with Facing everyone's skepticism and curiosity, Jiang Li explained fluently:..., adds pressure through Hearing Director Sun's words, he muttered in frustration, "Damn, if I knew..., and ends on.
If you want the clearest chapter reference, go to Chapter 92. Early on, Jiang Li, lightened from any task, had plucked a few leaves from the...; later, the chapter leans on She then produced a book from somewhere and began flipping through it on....