I'm slowly composing a story journal for a six-character PS run. Three characters are mine, three my dad's. (I haven't really written much about his characters except from my characters' PoVs.)
The trick is that my three are all writing their journal, and they need to have different voices and styles.
I started with Tiffany Teine, human mesmer, and wrote it in the first-person because just made the most sense.
But I can't write them all in the first-person or that would get confusing on PoV switches.
So! Three characters, three different kinds of PoV that reveal things about each character.
Tiffany Teine is a mesmer, and in my headcanon mesmers need to keep a grounded sense of self so they don't get lost between all their illusions and forget which one is real. So, she writes in first-person - "I did X." She's grounded inside her own head looking out at the world.
However, Ninuvinan tries to keep herself straight with other people; she's currently struggling with letting other people tell her what to think and believe, so she writes in the third person to help with that. Caithe said the Nightmare Court are evil and irredeemable; Ninuvinan, however, is a separate person and doesn't necessarily believe that.
Eveanin is a guardian, and she joined the Vigil; her whole theme is protection and loyalty and saving lives. She's looking at herself to see what she can do to better the world; what's her duty in this situation; how can she help. She writes in the second person, almost talking to herself to remind herself what all needs to happen but also what her limits her. What can YOU do to help? Don't worry about everyone else, what is YOUR duty? Don't try to do everything yourself; others will handle that, what can YOU do?