Prompt the Fourth

I have been loving the prompts for their very variety. But I feel like the most challenging writing prompt may actually be coming up with a writing prompt. I find that funny. Here is my prompt. I hope it is up to snuff.

Pick a book that you love. A book that you have read multiple times because you love the story. Write the equivalent of a fan fiction piece that is based on the book. This could mean writing a different ending, prolonging an existing scene, adding a prequel or epitaph, or whatever else. But do this without trying to mimic the actual writing/writer.