One idea could be a story about a group of misfit animals who form a band. There's a guitar - playing squirrel, a drumming rabbit, and a singing bird. They face challenges like finding a place to practice without getting chased away by other animals. Another could be a story of a lost puppy's journey to find its way home, with various animals it meets along the way either helping or hindering it.
Perhaps a story about a scientist who is working on a teleportation experiment. However, something goes wrong and instead of teleporting, he turns into a bird. He then has to figure out how to fly, find food as a bird, and build a nest. All the while, his colleagues are trying to figure out what happened to him and how to reverse the transformation. He experiences the freedom of flight but also the dangers that birds face like predators and bad weather.
One idea could be an OC (original character) who is a small, timid mouse in the animal kingdom. This mouse has the unique ability to communicate with birds and convinces a flock of sparrows to help him gather food during a harsh winter. Another idea is an OC that is a chameleon who can change not only its color but also its shape slightly. It uses this ability to outwit a sneaky snake that preys on the smaller animals in the kingdom. And a third idea could be an OC that is a young deer with the power to run at extraordinary speeds. It becomes a messenger for the different animal groups, delivering important news about approaching danger or new food sources.
One idea could be exploring the lives of the animals after the events of the original story. Maybe the pigs' regime becomes even more tyrannical and some of the younger animals start to secretly plot a revolution. Another could be a story from the perspective of a minor animal, like a mouse, who witnesses all the power struggles but is too small to be noticed. A third idea is to create an alternate ending where the animals manage to overthrow the pigs and establish a truly equal society.
Well, for animal transformation fanfic, you could have a story where a person transforms into a cat. They would then have to adapt to the feline lifestyle - climbing trees, chasing mice (or toys that look like mice), and napping in sunny spots. Or perhaps a transformation into a dragon. This would involve dealing with the huge size, breathing fire (if it's that kind of dragon), and being feared or revered by the people in the story's world. It could be really cool to write about how the character copes with this new identity.
One idea could be a story where a new villager arrives in the town and has a special power to communicate with the island's spirits. Another could be about a group of villagers starting their own little business within the game world. Maybe a fanfiction where the player character gets lost in a mysterious part of the island that no one has ever explored before.
Well, one interesting idea could be the concept of an animal remembering its past lives. For example, a cat in the fanfic might recall being a bird in a previous life and having different instincts and experiences that still influence it in its current feline form.
One idea could be a fanfic where the RWBY characters transform into animals. For example, Ruby could turn into a little red fox, with her speed and agility enhanced. Another idea is an animal - centered adventure where the team has to protect a magical forest full of rare and mythical animals. They might encounter a giant griffin or a group of intelligent ravens that can communicate secrets about the Grimm.
An 'animal body swap fanfic' might include a story about a snake and a mouse swapping bodies. The snake in the mouse's body would be terrified of being so small and vulnerable, while the mouse in the snake's body would have to figure out how to slither and use its new senses. Also, a fish and a turtle could swap. The fish in the turtle's body would be confused by having a shell and being able to move on land, and the turtle in the fish's body would have to deal with swimming in a whole new way and living in a different aquatic environment.
Perhaps a story where a human is stranded in a world full of only prehistoric animals. The human has to use their wits and knowledge from the modern world to survive among dinosaurs and other ancient beasts. They might figure out how to make tools from natural resources to protect themselves and find food.
One idea could be to explore what would happen if the Miraculous powers were transferred to animals. For example, a cat could become the holder of the Cat Miraculous and have to save Paris in a very different way than Chat Noir. Another idea is to create a story where the animal kwamis interact more directly with regular animals, like Tikki befriending a group of ladybugs and teaching them to help in small ways.