Gwen could be a great addition. She could be the voice of reason when Ben and Vilgax are at odds or she could have her own powers play a role in the story. Grandpa Max is also a good choice. His wisdom and experience could add depth to the fanfiction, especially when dealing with Vilgax. Another character could be Kevin. His ability to absorb energy could create some interesting interactions with Vilgax and also provide a different kind of friendship or rivalry dynamic with Ben.
Power struggle is a common theme. Vilgax is always after more power and often clashes with Ben or other powerful beings in the fanfics. Another theme is revenge. Since Vilgax has been defeated by Ben many times, he often seeks revenge in these stories.
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.
Ben Tennyson would most likely be one of the main characters as he is the central figure in the Ben 10 series. Gwen, his cousin, and Kevin, his friend, are also likely to be main characters. They often accompany Ben in his adventures in the Alien Force series.
One possible plot could be that Naruto and Ben Tennyson are somehow transported to each other's universes. Naruto, with his ninja skills, could be intrigued by Ben's alien forms and their powers. Ben, on the other hand, would be amazed by the chakra system in Naruto's world. They might team up to fight a common enemy that threatens both their worlds, like an alien force that has found a way to use chakra for evil purposes. This would lead to a lot of action -filled scenes where Naruto uses his jutsus and Ben transforms into different aliens to combat the threat.
One idea could be exploring the backstories of the aliens more in - depth. For example, how did Four Arms become so strong? Another could be a story where Ben has to team up with his enemies to fight a greater threat. Maybe Vilgax and Ben have to work together against an even more powerful alien race.
One popular 'Ben 10 Vilgax fanfic' could be 'Vilgax's Redemption'. It shows a different side of Vilgax where he tries to change his ways. Another one might be 'Vilgax vs. the New Aliens' which has some great action scenes with Vilgax facing off against newly introduced aliens in the Ben 10 universe.
Well, aside from the main trio, characters like Vilgax are often included. He's a powerful villain and can create a lot of conflict in the story. Grandpa Max is also a good character to add. His wisdom and experience can guide Ben in difficult situations. And then there are the aliens themselves. For example, Rath is a very popular alien form of Ben, and fans like to write stories that focus on his wild and unpredictable nature.
Well, a plot could be that Vilgax gets amnesia and Ben has to decide whether to take advantage of this or help him. This could lead to a whole new dynamic between them as Ben tries to figure out what to do. Also, a fanfiction could explore what would happen if Vilgax became a mentor to Ben in a strange, alternate universe. They could train together and Vilgax could pass on some of his knowledge, but also try to manipulate Ben for his own ends. Or, perhaps a story where Vilgax and Ben are both stranded on a strange planet and have to work together to survive, all while dealing with their mutual distrust.
Gara and Four Arms would have an interesting interaction. Gara, with his sand powers, is used to being in control and a bit of a loner. Four Arms is all about brute strength and action. When they meet, Four Arms might challenge Gara to a test of strength, which Gara would initially be hesitant about. But then they could find common ground in protecting their respective worlds. Four Arms could show Gara a more straightforward way of fighting, while Gara could teach Four Arms about using the environment to his advantage with his sand.