I know him. I know his personality. I spend an hour every week arguing with him, after all.

I think I probably know him too well, because he hasn't been very good recently at keeping his crap out of my therapy. He's arrogant, and competitive, and stubborn, and those parts of him don't really belong in the therapy room. They aren't helpful to me.

But I also think that if you do a lot of relational work you are inevitably going to end up knowing your T - you will certainly get to know their personality quirks, their sense of humour, their mannerisms... Even if you don't know anything about of the details of their life.