Comrade, you make some good points.

I hadn't thought of his relationship with L. This is something that came up in my working with ex-T and ex-MC, actually. And now, with Dr. T and his backup, R. With R, at one point, I granted her permission to share with Dr. T. But then there was one session where I shared a lot and felt uneasy about her telling Dr. T about it--like I told her I'd tell him in my own way, but was afraid of what she'd say. So temporarily revoked my permission (she was completely fine with it). Ex-T would never share something unless she asked permission explicitly. Later, I found out ex-MC had shared a bunch with ex-T that I didn't know about, which felt really awkward.

Scarlet, something you may want to ask him about is how much he's going to share with L. Are you going to feel free to say whatever you're feeling to him--like if you're angry at L, do you feel you can speak your mind to him without wondering if he'll take it to L later? Would he be OK if you said, "Please don't share this with L"? Or, even if you're fine with him sharing anything, is there a concern that he might be defensive of L? Just some things to consider.