Well, start by gathering inspiration. You could watch shows or read books with similar characters or themes. For building up a rachelfish fanfic, you might want to create a detailed outline. Decide on the beginning, middle, and end of the story. For example, the beginning could introduce Rachel and Fish in an unexpected situation, like being stranded on an island. Then, in the middle, they face challenges and grow closer. And at the end, they achieve something great together.
To build up a rachelfish fanfic, begin with the characters. Rachel might be a kind - hearted but a bit clumsy girl, while Fish could be a wise and mysterious creature. Develop their backstories. Then, think about the setting. Is it a modern city, a magical forest, or a far - off planet? Once you have these elements in place, start writing the story. Let the dialogue between Rachel and Fish be natural and show their unique personalities. You can also add some twists and turns to the plot to keep the readers interested.