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
Sometimes I just talk to myself.
Sometimes I talk with a random character. I can feel agency (or illusion of Independent agency) from anyome at this point, whether I want an anime waifu to “talk back” or to play out a dialogue I’m supposed to have with an IRL person soon.
And sometimes I talk with my inner companions. There are a few characters I have built stable, genuine relationships with over years.
Btw. at some point I started seeing my mind as a process rather than an entity (or set of entities). And like in other complex processes, it would be strange if we couldn’t observe any internal contradictions in it.