A new species series fanfiction could be about a species that has the ability to shape - shift. For instance, in the story, this new species lives secretly among humans, and only a few people start to suspect their existence. As the plot unfolds, a young journalist tries to expose them, but in the process, she falls in love with one of the shape - shifters. Another example is a fanfiction about a new species of flying creatures that live on a floating island. A group of adventurers go to explore the island and end up having to deal with the complex society of these flying creatures.
There are many possibilities. For example, a new species series fanfiction might center around a species that has evolved to live in a world with extreme cold. These creatures have unique adaptations like fur that can change color to blend in with the ice. The story could follow a scientist who is studying them and discovers that they have a complex language and culture. Or, it could be a fanfiction about a new species of sentient plants that can move and communicate. A gardener stumbles upon them and has to figure out how to co - exist with these strange new plant - beings.