If two characters are having a conversation and the POV character suddenly remembers something another character said, how would you display that quote? If I use quotation marks, the reader might think that third character is there and talking. I think italics would work, but I've read that I should never, ever use them except to stress one word. An example from the top of my head: "Mom loves my husband," said Mary. That man is a two timing, worthless skunk, Mom had said. She was always happy to tell Beth her true feelings when Mary wasn't around. "I'm not so sure about that," Beth said.