One of my therapists asked me about the sexual fantasies I had about him in an ET discussion. I initiated the topic but he asked for the details. I did not mind and actually found it meaningful to think it through again in session, I felt the fantasies carried information about my sexual/romantic needs at the time, and more. It was just one session and we never spoke about it again.

I agree that it would be inappropriate for a T to ask a client about their sexual fantasies (whether about the T or in general) if it is not initiated by the client or is very obviously and directly linked to an ongoing issue that is being discussed.