I have developed a rule about these; because they are explicitly not meant to go onto the stage, I write them from a different perspective than my stage text.

Hi, I followed a link from voleuse. This is really interesting. I used to have a lot of trouble with developing my characters fully and doing the pre-writing/character-building stuff other people do. I say used to, but it's really something I'm improving on but still struggling with. I tend to want my characters to spring fully into being so I can just write what's already there instead of having the kind of scary responsibility of actually BUILDING the character like I do the plot. But I've found a couple things that have helped me to loosen up that part of my brain and write the exploratory stuff without the pressure of needing to write something "usable." One is to write things in second person, which I use for doing more specifics and details. And the other is to write things in a fairy tale format, starting with once upon a time and removing names and purposely keeping things at a distance and on a less detailed more metaphorical level, which I use for an overall grounding of each character's journey in the story. And I didn't really think so much about WHY doing those things made it easier for me, but I think it's what you said about them making it so explicitly not for "the stage." It kind of fools my mind into letting go and thinking...it's okay, there's no pressure, this is a separate, safe space.

Anyway...great post.