One possible fanfiction could be about Rex's adventures in a new, uncharted area where he discovers a strange new type of E.V.O. He has to use his powers in creative ways to deal with it and learn more about this new threat or ally.
Definitely include Six. He's Rex's mentor and his combat skills and knowledge would be valuable in any crossover. If it's a crossover with a superhero team, he could offer strategic advice.
One idea could be a crossover with Ben 10. Rex's nanites and Ben's Omnitrix could lead to some interesting power clashes and team - ups. They could face a common enemy that requires both their unique abilities to defeat. For example, an alien - nanite hybrid villain.
Fanfiction about Rex and Six could also involve a mission where they are sent undercover. They have to pretend to be ordinary people in a community that is on the verge of being overrun by E.V.O.s. They need to figure out how to stop the E.V.O.s without blowing their cover, and in the process, they learn more about each other's personalities outside of the battlefield.
In a fanfiction crossover, they could end up in each other's universes by accident. Ben finds himself in a world full of EVOs and has to rely on Rex to get back home. Meanwhile, Rex is intrigued by the Omnitrix and tries to figure out how it works. They face many challenges together, like dealing with Rex's old enemies who see Ben as a new target.
At first, they could be rivals. Ben might think Rex's nanites are too unpredictable, and Rex could see Ben as a bit of a show - off with his Omnitrix. But as they face common enemies, they start to respect each other. For example, when they're both captured by a powerful villain, they see how the other fights and starts to understand their strengths.
In a post - apocalyptic world, Generator Rex was on a mission. Rex was also exploring the same area. They both heard rumors of the Black Knight. When they finally met the Black Knight, he was not what they expected. The Black Knight had a code of honor. Rex was intrigued and Generator Rex was curious about his technology. They started to exchange knowledge. The Black Knight taught them some ancient combat techniques and in return, Generator Rex shared his knowledge of advanced machinery. Rex learned a lot from both of them and they became friends, vowing to protect the world together.
Yes, there are some really interesting ones. You can often find them on fanfic platforms. Just search for 'Fire Emblem crossover generator Rex' and you'll likely come across a few. Some might focus on Rex joining the Fire Emblem world in unique ways, like being a mysterious new unit with special abilities.
Another plot could be that an interdimensional rift opens up, and it's causing chaos in both Ben's and Rex's worlds. They discover that the source of the rift is related to the technology of both the Omnitrix and the Nanites. Together, they journey through the rift to find the cause and close it. Along the way, they meet alternate versions of themselves and their friends, which adds an interesting twist to the story.
It could be Ben when he transforms into Alien X. Alien X has near - omnipotent powers. He can manipulate reality on a cosmic scale. In a crossover, he could potentially use those powers to control the Nanites or even restructure Rex's powers in some way. However, he's also very difficult to control, so it's a double - edged sword.