To write a great 'Young Sheldon fanfic', start by researching the show. Watch episodes to get a feel for the setting, the time period, and the other characters. When creating your story, think about what makes Sheldon unique. Maybe you can create a story where he has to overcome a fear that is specific to his character. You can also add some new characters to the mix, but make sure they blend well with the existing ones. And make your story engaging by having a clear beginning, middle, and end. Write dialogue that sounds like it could come from the show, with Sheldon's precise language and quick - witted responses.