For a Generator Rex vampire fanfiction, when creating characters, start with the vampires. Decide if they are traditional vampires or have some unique twist due to the world of Generator Rex. For example, they could have nanite - based powers instead of just the typical vampire abilities. Make their personalities distinct. Some could be brooding and mysterious, while others could be more outgoing and friendly despite their vampiric nature.
Create side characters that add depth to the story. A vampire hunter character could be interesting. They could have a vendetta against vampires but then learn to work with Rex when they realize there are bigger threats. Also, consider creating a vampire leader character. This character could be both menacing and have a complex backstory, like they were turned into a vampire against their will and are now trying to find a way to reverse it while also leading their vampire community.
Another story could be set in a post - apocalyptic world where vampires have emerged as a result of some mutagenic event related to the nanites. Rex, being the only one with the ability to control his nanites, has to find a way to coexist with the vampires. He could encounter a vampire who was once a scientist and together they try to reverse the vampiric transformation in some people.
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.
One important aspect of creating an engaging Generator Rex OC fanfiction is to focus on character relationships. Your OC can interact with the existing characters in different ways. They might start as rivals with Rex but gradually become friends. Also, describe the world vividly. Talk about the different EVOs, the Providence base, and the chaos in the cities. This will draw the readers in. Another tip is to add some mystery. Maybe your OC has a secret power that they don't fully understand yet.
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.
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.
Writers can make vampire characters more compelling by exploring their moral compasses. Some vampires might have strict rules about whose blood they drink, while others are more reckless. Their relationships with other vampires and humans are crucial too. A vampire who has a complex friendship with a human who is aware of their blood - drinking habit can be very engaging. Additionally, their powers related to drinking blood, like being able to sense the health of a person by their blood scent, can add depth.
First, combine the unique elements of both worlds. For example, the technology from Generator Rex and the supernatural aspects of Highschool DxD. You could have Rex's nanites interact with the devil powers in DxD. Maybe a character from DxD gets infected with the nanites and gains new abilities. This creates an interesting conflict and opportunity for character development.
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.
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.
One idea could be a crossover where Generator Rex's nanites interact with the X - Men's mutant powers in unexpected ways. Maybe the nanites start to adapt and mimic some of the mutant abilities, causing chaos and confusion among both groups.