That's pretty much all we discuss. Some people do dream analysis, we do sexual fantasy analysis. It's amazing how much you can learn about yourself by really digging into your sexual fantasies with the person you're fantasizing about, i.e. "the paddle you were spanking me with represented my shadow and the butt plug represented my anger at my mother." I'm totally kidding

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I've heard it is sometimes useful to discuss, I bet this is in certain limited circumstances though. If I kept fantasizing about sex with my T in my childhood bed, or T abusing me during intercourse I might bring that up, being careful about the words I use so it doesn't come across as seductive. If I fantasize about simply crossing the room and screwing his brains out, best to keep those details to myself I think.