I work in healthcare so we know a lot of people in common, but it wouldn't help me to be overly secretive about names, as she can probably work it out anyway. I trust her to keep things confidential. I use first names only, but it can't be helps that sometimes one or other of us speaks about someone we both know in different contexts. I've even shown her family photos and I know a lot about her family too. I prefer that, rather than anonymity and/ or a blank slate. It seems that the more we share, the more connected we feel and the more effective my therapy.