This isn't an unc-slop post. This is a post about managing multiple characters in creative writing.
Everyone should watch Teenage Mutant Ninja Turtles (TMNT). Which comic, movie or TV series should you watch first? At this point, there's so many, and I'm not a super fan. My favorites are the 2003 animated series and the first two live-action movies.
When I was kid, everyone knew about TMNT. Everyone loved TMNT. And there was an interesting question you could ask anyone and learn a lot about them.
"Who is your favorite turtle?"
Your answer revealed something about you whether you realize it or not. 9 times out of 10, your favorite turtle tells people what your personality is.
So, in case you are unfamiliar with TMNT because you're under twenty-five, there are four turtles. They each have one dominant personality type.
Leonardo = Responsible
Michelangelo = Carefree
Donatello = Intellectual
Raphael = Emotional
The first thing you'll notice is that each personality is distinct. With TMNT in particular, the personality types are exaggerated so that you immediately associate the character with the trait. This helps audiences recognize and remember the characters, and if you recall what I said earlier about people having favorites, it helps audiences immediately identify one character they like.
If you look at these personality types, you'll notice that each personality type has one opposite. Responsible and carefree are opposites. Intellectual and emotional are opposites.
This is where character dynamics come in. By pairing the opposing personality types in a scene together, they contrast each other and exaggerate their characteristics. This can also lead to conflict.
The other personality types can make complementary combinations. See, these personality types I've listed are their dominant personality trait, but not the character's only trait. They have some range. For example, the responsible character has capacity for intellectuality and emotionality, but it takes pairing one of the complementary personality types with them to bring it out. If you put the Leonardo in a scene with Raphael, you can Leonardo get heated and frustrated. If you pair Leonardo in a scene with Donatello, you can see Leonardo's appreciation technology and intelligence gathering.
Pair any two characters to reveal interesting dynamics.
Michaelangel (carefree) brings out Donatello's (intellectual) fun side. Michaelangelo also encourages Raphael (emotional) to be a little wild.
So, any time you're managing multiple characters in a scene, it helps to simplify them to their dominant personality trait and ask yourself, "how do these personality traits mix?"
Don't limit yourself to these personality types I've describe above. Make your own if it suits you. Maybe lawful, neutral, and chaotic. Maybe final happy, angry, and sad. Maybe brave, wise, kind, and cunning. The key words that make sense to you will probably suit you very well.
I recall some classical Greek idea about four humors explaining four personalities. If you're curious about the four humors, look up something called the Four-Temperament Ensemble.
Christianity has a concept of seven sins and seven virtues. Those are some really good words to think about. Each sin describes an aspect about the human condition, and each virtue describes a discipline one needs to manage it.
In the Wizard of Oz, Dorothy wants to go home. Her other companions? Brains, courage, and heart. There's an interesting combination in there somewhere.
In a story I'm writing right now, I am juggling seven characters. Three of them have been pushed to the background, but they could be described as heart, courage, and brains. Of the other four, one is responsible, one is carefree, one is emotional. The last one is a wildcard; to be determined. It's probably pride. Using these key words helps to reduce the cognitive load of seven characters while still keeping their presence distinct and their interactions meaningful.
If you want to know how to make a likable character, which is also important, I wrote a review about an anime where I break down what makes a likeable character here: Anime Recommendation: Kimi Ni Todoke.