One Way to Write

Creating COMPLEX Characters

Option 2: Make a long list of traits/personalities. When you want to build a character, pull from this list randomly or based on preference. Mix and match until you reach a result that fits into your plot and preferences.

*Feel free to start with traits based on someone you know or a celebrity or a character from other media to help get you started. Or start from scratch. Whatever works for you.
*Also, don't feel obligated to make an opposite to every trait/personality. Perhaps this character doesn't really have contradictory personalities. Or perhaps the one situation where this trait would show doesn't happen in the story.

So, here are three of my characters that I've already written and the traits/personality copies that would come out of them: 

Hitori:
- Mute and insecure
- Confident and stylish 
- Overimaginative and kinda crazy
- Dark and morbid
- Pure and sweet
- Perverted/romantic

Natsu:
- Possessive and controlling
- Arrogant and cruel
- People pleasing/selfless/caring
- Quiet and pessimistic
- Annoyed, easily irritated
- Indifferent, apathetic

Eran
- Hot tempered, violent
- Indifferent, apathetic
- Insecure, anxious
- Logical, intellectual, emotionless
- Egocentric, selfish

As you can see, some of the personalities have opposites in the same list. Hitori is pure and sweet yet dark and morbid, Natsu is arrogant and cruel yet selfless and eager-to-please, Eran is egocentric and selfish yet insecure and anxious. Others don't have opposites. For example, while quiet and pessimistic, Natsu does not have a talkative and optimistic side. 

Context

Now onto when these sides come out and why they exist, because you can't just slap down some personalities or traits without deciding their context and background. 

Eran is egocentric and selfish. He wants things done his way on his time because his wants and needs are more important than others'. But he hides and ignores his insecure and anxious side which only comes out in front of his boyfriend. He is constantly doubting that he can satisfy people and that he's deserving of love as he didn't grow up receiving it. He's terrified of disappointing people. His selfishness acts as a shield so that he always feels in control and like he has the upper hand. 

Dominant Traits
and
Personality vs Personality

In the webtoon Hotel Phryne, there is a scene where the copies are arguing with their respective opposite copies because they hate that side of themselves. In deciding what trait is dominant, imagine these copies fighting and arguing. Who ends up winning?

Eran's insecure copy would cower, be full of doubts, and probably agree that he was useless if snapped at by the selfish copy, even if the insecure copy thought the selfish was flawed too. 

Sometimes it's a bit hard to tell which copy would win. Who would come out on top when it comes to Natsu's people-pleasing and caring side versus his arrogant and cruel side? The caring side would scream, "People will be miserable with you around. You'll be alone forever." The cruel side would yell, "You're a suck-up who pretends to care even when you don't. You just want a clear conscience." 

In this uncertain case, you have to choose based on plot or the personalities of surrounding characters. Or you may want to try writing both or making one dominant in a situation and the other dominant in another. Natsu is arrogant and cruel to people who don't respect him or others. When it comes to his family and friends, he's caring and eager-to-please. And, for the record, when it comes to everyone else, he's indifferent and apathetic. If someone who bad-mouthed his friend was bleeding on the street, he'd walk away or maybe watch them die. If it were a friend or family member, he'd jumped to their aid immediately. If it was a stranger bleeding out, it'd probably take him a minute to decide whether to help out or not. But if you asked anyone who knows him, what would Natsu do, they'd say, "He's sweet. He'd help the person, of course!" 

Breaking up our characters into copies based on a single personality helps us to see their extremes. Our characters will likely not show their biggest extremes in our story (unless it's a psychological thriller or they have a mental illness), it helps to know. 

Putting it All Together in the Hotel Phryne Scenario

In Hotel Phryne, there would be a Hitori who says nothing the whole time and just cries. There would be a Hitori who believes he can definitely prove that he's real and tries to come up with a plan. There would be one thinking of maybe seeing if there are ghosts to call for help in this supernatural place. There'd be a copy suggesting they all stab themselves to see if that solves the problem. There would be a Hitori saying it's okay, they can all just live together including the fakes. One would be desperately professing his love and promising to do anything for Natsu to pick him as the real one. If in this world, there was actually a true Hitori with all the traits combined into one as in real life, he'd be clinging to Natsu, trying to decide what to do for an hour until finally asking Natsu what he thinks is best to do and putting his trust in Natsu. As you can see, the real Hitori is far from any extreme, but he's still the culmination of all these other personalities. 

TL;DR: Read Hotel Phryne.

What personality copies would exist in your characters' Hotel Phryne Scenario?  

And what topic would you like me to cover next?