Write about what super-heroes and super-villains do in their spare time or on their days off. Feel free to make it funny: maybe Voldemort enjoys yoga, or Wonder Woman writes a blog.
Write a romance. You can make it anything between rom-coms and Romeo and Juliet, but make sure there are two characters in love, and at least one obstacle (internal or external) to that relationship.
Write about the first day of school (can be elementary school, middle school, high school, college, or anything else). You can make this a shining moment for your character, or you can make it awkward and embarrassing. Have fun with it!