For me there’s two separate participants, a ‘talker’ and a ‘listener’. My mind identifies more with the talker, because that’s the one that has agency. Since there are two participants, both of which are me, I talk in 1st person plural (‘we’ve got to do …’, 'we thought about this earlier’). I stopped being afraid of being alone after I started having an internal dialogue around the age of 11, since having a second participant in the conversation meant I was always in company.
Edit: Wow, looks like there’s a lot more diversity in this than I was expecting
Wow, that’s really sophisticated. I don’t think my mind would have the capacity/bandwidth to play a totally independent, second active participant
In fairness, I have a weird capacity that’s the opposite of aphantasia. Some people can’t picture things in their minds, the same way some people don’t have an inner voice. I call my thing hyperphantasia.
When I’m reading a book (or writing something), I can see and hear things as they’re described to the extent that I stop perceiving the real world fully. If the author describes smells, I sometimes get those. It’s a very immersive experience beyond what I’ve seen other people describe as their inner imagery. I’ve even gotten hints of feelings on skin if I’m deep enough and the descriptions are right.
I know I’m not the only person that experiences things that way, but it does seem to be rare based on responses when I talk about it online.