Lizzie Andrew Borden

I know what she used to do sometimes. She kept her best cape she wore on the street in there, and she used occasionally to go up there to get it and to take it into her room. She kept a great deal in the guest room drawers.

The historical novelist has to consider what has actually happened, while the SF writer is dealing in possibilities, but they are both in the business of imagining a world unlike our own and yet connected to it.