A 'human x noivern fanfic' could be about a human who has the ability to communicate telepathically with Noivern. They team up to stop an evil force that is threatening the Noivern's natural habitat. Along the way, they learn about each other's cultures and the human gains a new perspective on the world of Pokémon, specifically the Noivern species.
First, you need to create your characters. Decide on the personality of the human, whether they are brave, shy, or curious. For the Noivern, think about how it will interact with the human. Then, come up with a basic plot. It could be something as simple as the two of them going on a journey together.
One idea could be a story where a human scientist is studying sharks and forms an unexpected bond with a particularly intelligent shark. They communicate in some unique way and end up helping each other, like the shark leading the human to a hidden underwater treasure which in turn helps the human protect the shark's habitat.
One idea could be a story where a human trainer has a special bond with a Pikachu that allows them to communicate telepathically. Another could be a human getting lost in the Pokemon world and having to team up with various Pokemon to find their way back home. Or perhaps a story about a human who discovers they have the power to transform into a Pokemon.
One idea could be a story where a human hunter is saved by a Barioth during a particularly dangerous hunt. The Barioth, instead of attacking the human, senses a greater threat and defends the human. This event then forms an unlikely bond between them, and they start to communicate in a unique way, perhaps through body language and mutual respect for each other's hunting skills.
A plot could involve Isabelle having special powers that she doesn't fully understand. A human scientist discovers her and tries to study her, but they gradually form a bond as the human helps Isabelle understand her powers better. This could lead to a story of friendship and self - discovery against the backdrop of a world that doesn't quite understand their relationship.
One idea could be a story where a human scientist discovers a female dinosaur in a prehistoric world and they form an unlikely bond. The human helps the dinosaur avoid some natural disasters in that era, and they communicate through simple gestures and expressions.
One idea could be a story where the human discovers a hidden world of giant girls and has to learn their ways to survive. Maybe the giant girls are protectors of nature and the human has to convince them to save his own world from destruction.
One idea could be that a human scientist is working on a project related to Mewtwo's powers. They start to communicate on a deeper level, and Mewtwo begins to see the human as an ally rather than an enemy. The human, in turn, tries to understand Mewtwo's complex emotions.
A mermaid x human fanfic could start with a human sailor getting lost at sea. A mermaid finds him and guides him to safety. As a result, they develop a relationship. They might face challenges like the mermaid's family not accepting the human or the human having to keep the mermaid a secret from his own kind. Another plot could be a young girl who has always dreamed of mermaids and one day, while swimming, she actually meets one. They become friends and the girl starts to learn about the mermaid's culture and way of life. And yet another idea is a mermaid who is curious about the human world above water and she meets a human who is equally curious about her world. They embark on a journey of discovery together.
One plot idea could be a human soldier being captured by a Viper. Instead of killing the human immediately, the Viper discovers an unexpected connection with the human. Maybe they both have a shared memory from a past encounter with a third alien species that makes the Viper spare the human. Then, they form an uneasy alliance to face a greater threat in the Xcom universe.