To illustrate my query, let us imagine I am writing Double Indemnity, that thrilling tale of murder and deception that was made into an excellent film in 1944.
Insurance salesman Walter Neff (that's with two ‘f’s like Philadelphia), meets the glamorous but neglected Phyllis Dietrichson when he calls to arrange the renewal of her husband’s motor insurance. They start an affair that leads to murder.
So I’m onto Chapter 2, where they meet. The narrative, which is in the first person, contains pieces like these:
Mrs Dietrichson poured some iced tea…
I told Mrs Dietrichson that I’d call back tomorrow night when her husband would be home.
”Mrs Dietrichson, that’s a honey of an anklet.”
Once the affair starts, however, he ditches the formal Mrs Dietrichson for the more intimate Phyllis. Now it becomes:
I met Phyllis in the supermarket as arranged.
He told me that Nino had been to see Phyllis every night at her house.
”I tried to keep Phyllis out of it.”
Neff can’t refer to this woman as Phyllis from the outset, as he doesn’t yet know her first name. But when they become intimate, he would not call her Mrs Dietrichson either.
Would I just go ahead and change the name of the character when the protagonist changes the way he addresses her, or should I stick with one or the other?
I suspect the former, but some clarification would be welcome - thanks