To write a goonie fan fiction, you need to understand the world of the Goonies. Research the movie's setting, the relationships between the characters, and the overall tone. You can also draw inspiration from other adventure stories. When writing, focus on creating engaging dialogue for the characters. Since they are kids with big personalities, their conversations should be lively and full of humor. Also, describe the action scenes vividly so the reader can feel like they are part of the adventure.
Begin by choosing a central theme for your goonie fan fiction. It could be friendship, like how the Goonies' bond helps them overcome obstacles. Next, plan out your story structure. Decide on the beginning, middle, and end. In the beginning, introduce the situation or problem. In the middle, build up the tension and the characters' efforts to solve the problem. At the end, resolve the situation in a satisfying way. Don't forget to add your own unique twists and turns to make it stand out from other fan fictions.
First, re - watch the original 'Goonies' movie to get a fresh feel for the characters and their personalities. Then, come up with an original idea, like a new adventure or a different take on an existing plot. For example, you could write about what would happen if the Goonies found another map leading to a different treasure. After that, start writing and don't worry too much about making it perfect at first.