To start writing my sister's keeper fanfiction, begin with a strong opening scene. Maybe it's a moment of crisis for the sister, or a heart - to - heart conversation between the siblings. You also need to decide on the tone of your fanfiction, whether it's going to be more dramatic, hopeful or something else. And don't forget to create a rough outline of the main plot points you want to cover.
First, re - read the original book or watch the movie to get a fresh feel for the characters and the story. Then, think about a unique angle or concept that you want to explore. It could be as simple as focusing on a particular relationship or a what - if scenario.
Begin by identifying what aspect of the 'my sister's keeper' story you are most passionate about. Is it the ethical dilemma? The family dynamics? Once you've decided that, you can start building your story around it. For example, if you're interested in the ethical dilemma, you could start with a situation that challenges the existing ethical boundaries in the story. Then, introduce your characters and start developing their personalities based on how they react to this situation. Also, it's important to establish the setting clearly, whether it's the same as the original or a new, re - imagined place.