Have you ever seen those videos on YouTube where an artist takes multiple clips from a specific movie and rearranges them to create trailers for it across different genres? While most fiction pieces tend to fit tightly within one particular genre, a good story always has several other elements lying just beneath the surface, and it takes quite an inventive mind to latch onto those elements and manipulate them one way or another. On one hand, you might have a dramatic film with plenty of tension and high stakes; clip together the few moments our characters are laughing / drinking coffee and attach an upbeat pop song to it, and you’ve got a romantic comedy. Take a story, throw in some darker color schemes here, just the right amount of music there, and you’ve turned a children’s movie into a horror (though, for those of us who grew up with 80s and 90s children’s movies, is there really much of a difference?)
You can do this with writing, too. Creativity often feels like magic, but sometimes it is also very much a science. Just by putting more focus on the right details, writing from just the right point of view, and twisting the audience’s expectations, you can completely change the themes and outcomes of a story everyone thought they knew.
Take a basic, familiar plot line (a fairy or folktale would probably be the best place to start) and rewrite it as a horror, fantasy, mystery, romance, etc. Make sure to experiment with elements such as point of view, imagery, world-building and setting, in order to make the most of the genre you’re hoping to portray.