Another plot could be Ben's first day at a new kindergarten. He's a bit shy at first, but then he makes friends with a group of kids who love building sandcastles in the sandbox. They all work together to build the biggest and most creative sandcastle ever.
Maybe in the 'ben 10 hypnotized fanfic', Ben is hypnotized by a mysterious force during one of his adventures. As a result, he starts having strange dreams that seem real and he's unable to transform into his alien forms properly. His grandfather and Gwen try different methods, like using ancient spells or advanced Plumber technology, to snap him out of it.
Another plotline could involve Ben and Albedo being forced to team up against a greater threat. They would have to put aside their differences and work together, which could lead to some interesting character dynamics as they learn more about each other.
There could be a plotline where they are in a competition of sorts. Maybe they are both trying to prove who is more powerful in the world of horror. However, as they compete, they start to understand each other better and realize that they are more alike than they thought. Another possible plot is that they are both haunted by the same entity, and they have to work together to break free from its control.
One possible plotline is that Ben Tennyson accidentally gets transported to the world of Fairy Tail. He has to figure out how to use his Omnitrix in a world full of magic. Another could be that the Fairy Tail guild discovers an alien device similar to the Omnitrix and they try to figure out how it works.
A plotline could be that Rook and Rayona are assigned to protect a special VIP from the galaxy. Along the way, they face various challenges like attacks from bounty hunters. Rayona might use her unique skills, and Rook his Plumber training. They start off not getting along well but as the story progresses, they come to respect and rely on each other. Another idea is that they discover a hidden civilization that is in danger of being destroyed by a natural disaster. They then have to figure out a way to save this civilization while also dealing with their own personal issues.
One possible plotline could be that Anakin is somehow brought back to the time when Ben and Rey exist. Maybe he serves as a mentor to both of them, using his own experiences of the dark and light sides of the Force. He could help Ben fully turn back to the light, and teach Rey some ancient Jedi techniques that were lost in her own training.
A third possible plotline is that Serena could look up to Ash as a role model. She might want to be like him when she grows up. So, she tries to imitate his every move in Pokémon training. However, Ash notices this and tells her that she should develop her own style. This could lead to a story arc where Serena discovers her own unique approach to Pokémon training and battling with the help of Ash's guidance.
His curiosity. Ben would be curious about everything around him. He might constantly ask questions like 'Why is the sky blue?' or 'Where do the ants go in winter?' This could drive the story forward as he explores to find answers.
One possible plotline could be that Renesmee is having trouble fitting in with both the vampire and human worlds as she's now a young adult. Another is that the Volturi are making a comeback with a new set of rules.
One possible plotline could be that Ben, as a girl, has to deal with the different social expectations. For example, his usual rough - and - tumble approach as a boy might not be as accepted in his new female form. He could struggle to be taken seriously when he tries to use his alien powers to save the day. Another plotline might involve his relationships. His friends might react differently to him, some being overly protective while others might be a bit more distant at first. There could also be a story where he has to learn how to handle the physical differences in combat or other situations.