I expect that any day now, I will have said all I have to say; I'll have used up all my characters, and then I'll be free to get on with my real life.
I consciously try to end my novels at a point where I won't have to wonder about my characters ever again.
I do write long, long character notes - family background, history, details of appearance - much more than will ever appear in the novel. I think this is what lifts a book from that early calculated, artificial stage.
For my own family, I would always choose the makeshift, surrogate family formed by various characters unrelated by blood.
The Amateur Marriage grew out of the reflection that of all the opportunities to show differences in character, surely an unhappy marriage must be the richest.
I don't want to say I hear voices; well, actually I do hear voices, but I don't think it's supernatural. I think it's just that when characters are given enough texture and backbone, then lo and behold, they stand on their own.
I'll write maybe one long paragraph describing the events, then a page or two breaking the events into chapters, and then reams of pages delving into my characters. After that, I'm ready to begin.
It's true that it's a solitary occupation, but you would be surprised at how much companionship a group of imaginary characters can offer once you get to know them.