The King in Yellow (fictional play, from The King in Yellow)
Who is the King? I know it's the primary mystery of the play for a reason, but that's what fanfiction is for! Why is he interested in Camilla and Cassilda? Is he in love with one or both of them? Basically, I'm looking for backstory fic here, and the great thing about this play is that it leaves lots of options open. If you'd prefer to focus on the other characters, that's okay too- I just really want fic for this fandom!
Misery Chastain Series (fictional books, from Misery)
I don't know about you, but I LOVE the gothic turn the last book took, and would like to see that angle explored. What if the cult follows her into her daily life back home, or if some of the old villains turn out to be even wickeder and more dangerous than previously expected? (Woo, ghost pirates!) When it comes to shipping, I've always thought the love triangle had an easy solution. She loves both her suitors, they both love her- who says she has to choose? So if there's a fic author out there happy to write some spooky harem romance, I fully salute you!
Thirteen Tales of Change and Desperation (fictional book, from The Thirteenth Tale)
Anything goes here, honestly. Okay, okay, I'll be a little more specific- Vida Winter writes such heartbreaking, haunting fairy tale adaptations that I just want more, in whatever form. Some potential things to write about might be what happens when metaphorical fairy tale characters get actual fairy tale magic, or more fairy tales in Winters' style, or just what the heck the thirteenth tale was! Don't feel limited to this list, of course.
All of Them Witches (fictional book, from Rosemary's Baby)
I'm really open to anything here, mostly because there's so much potential. What were the forces that birthed all these cults? Do good witches exist in this universe? What do they worship? And how did the author get all of this information anyway? All these answers and more are in your hands!