@Realm I'd consider Sherlock if it was the films as opposed to the BBC series. Game of Thrones may work. Other fandoms I could do would be Harry Potter, Doctor Who, Logan (2017), MCU shows/movies, Dragon Age, Heroes, Hunger Games, Law and Order SVU.
I also have been itching for a Victorian Era RP and we could probably give that some kind of supernatural twist too, maybe even involve train travel somehow (an alternative to road trip somehow?).