I came across the term faction, a story, film, or television programme that is a mixture of real and imaginary events or people However, faction is also used to mean a small organized dissenting group within a larger one, and I'm extrapolating future events, not inventing facts, so it seems to be only partially correct

Thanks, the linked question answers what I was looking for.

@PhilSweet Thanks. Please post that as an answer, I'll accept it.

@Reg That's more like what I was looking for. Can you post that as an answer with more details?