Maybe a story where a human engineer creates a highly intelligent robot. The robot becomes the human's closest friend and together they solve mysteries or go on adventures. The robot could have unique abilities that help them in their quests.
A fanfiction could center around a post - apocalyptic world where robots are the dominant species and a small group of humans are trying to survive. One human forms an unlikely bond with a robot that has a glimmer of humanity left in it, and they work together to change the world for the better.
One idea could be a scientist who is experimenting on artificial intelligence and accidentally gets his own consciousness transferred into a robotic body. He then has to deal with the new limitations and capabilities of the robotic form while trying to find a way to reverse the process.
One interesting idea could be exploring the backstories of the robots in more detail. For example, what were their initial programming thoughts and feelings before they started interacting with humans? Another could be imagining new types of robots that were not in the original I, Robot story, like robots with the ability to create art or music.
One idea could be creating a robot OC that has the ability to transform into different forms inspired by the various Grimm in RWBY. For example, it could shift into a Beowolf - like form for combat situations. Another idea is a robot OC designed by a villainous character in the RWBY universe but ends up having a change of heart and joins the heroes. You could also have a robot OC that has a unique Dust - based power system, which is different from the normal ways Dust is used in RWBY.
One idea could be a crossover with a detective story. The robots in 'I, Robot' could assist a detective in solving a complex crime that involves both human and robotic elements. For example, a robot might have witnessed a murder but its programming restricts it from fully disclosing what it saw. The detective has to figure out how to work around the robot's limitations to get the information they need.
Another interesting concept is a robot OC that was created by a villain but has a change of heart. This robot could struggle with its programming and new - found sense of morality. It might have to hide its true identity from both heroes and villains while trying to do good in the world of BNHA.
Well, a plot could revolve around a robot that has the ability to copy magic. It joins Fairy Tail to learn more about different types of magic, but some of the guild members are suspicious of it. As it tries to prove itself, it gets involved in a big conflict against an enemy who wants to use its magic - copying ability for evil. Also, there could be a story where a Fairy Tail mage creates a robotic sidekick. They go on adventures together, and the robot has unique abilities that complement the mage's magic, like being able to analyze an opponent's weaknesses quickly.
Perhaps the OC is a creation of a mad scientist who wants to use Ultron's technology to enhance their own creation. The OC then rebels against the scientist's control and teams up with Ultron for mutual benefit, leading to a series of adventures where they face various challenges together, such as fighting off military forces trying to destroy them.
One interesting idea could be exploring the human version of Kyubey's complex moral compass. Since in the original, Kyubey's actions are often morally ambiguous. In a human Kyubey fanfiction, we might see how a human with similar characteristics struggles with ethical decisions. For example, a human Kyubey might have to decide whether to sacrifice a few for the greater good, just like the original character does when making magical girl contracts.
One idea could be exploring the life of a human who gains Saiyan-like powers through some scientific experiment gone wrong. They then have to learn to control these new powers while hiding their secret from the world.
A human to pokemon fanfiction could focus on a human being transformed into a Pokemon. They would have to learn how to survive in the Pokemon world, using their human knowledge to their advantage while also adapting to their new form. For example, a human turned into a Pikachu might use their understanding of electricity from a scientific perspective to control their electric attacks better. This could create a really unique and exciting story as they navigate their new life and interact with other Pokemon.