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.
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.
Gwen would be a great character to pair with Alien X. Her magical abilities could complement Alien X's powers in interesting ways. For instance, when facing a threat that requires both brute omnipotent force and the finesse of magic. Another good pairing could be Kevin. His ability to absorb and use different forms of energy could interact with Alien X's power source in unexpected ways, like when they need to combine their powers to break through a powerful energy barrier.
Some of the alien characters themselves, like Heatblast or Four Arms, are also popular. Their unique physical characteristics and powers make them interesting to write about. For instance, Heatblast's ability to control fire can lead to all kinds of scenarios, from battling fire - based villains to using his heat to solve environmental problems in a story.
One common theme is friendship. The female alien often forms a strong bond with Ben, and they support each other through different situations. Another theme is power. The female alien usually has some unique power that plays an important role in the story.
I'm not entirely sure about the exact plot details of 'ben 10 ultimate alien the big story'. It might involve Ben Tennyson using his various alien forms to face some big threats and challenges, but that's just a general guess.
A villain could be a corrupted game developer from the real world who gets sucked into the Ben 10 universe. He uses his knowledge of coding and game design to create digital monsters that are difficult to defeat. He wants to take over the Ben 10 world and turn it into his own personal game realm.
One interesting story could be about an alien's unique adventure on Earth. Maybe it discovers a hidden power within itself while trying to adapt to human society.
It could be an alien bounty hunter. This bounty hunter has been hired to capture Ben in his stuck - as - alien form. The hunter might have some special gadgets or powers that make it difficult for Ben to escape. And he's not interested in Ben's well - being, just in getting the reward for bringing him in.
Power and responsibility is also a big theme. Ben has to handle the powers of his alien forms responsibly, especially when dealing with aliens. In many fanfics, there's also the theme of discovery. Ben discovers new things about the aliens, their cultures, and their abilities. For example, he might learn a new power from an alien that he can use in a different way. There's also the theme of cooperation, where Ben and the aliens work together to achieve a common goal, like saving a planet or stopping a powerful enemy.