I imagine being them

Try and have a conversation with them, or putting them in different scenarios to see how they react.

How would they react to someone eating really loudly in their presence? Irritated but they bite their tongue and tolerate it? Says something about them. They go up and tell the person to stop? Says something. They get so annoyed they punch the person in the face and leave ? Says something. Don't care at all? Says something.

Think of your friends and family. You don't necessarily define them as a list of traits, you know them through their work, their hobbies, places they feel safe, places they feel unhappy, needs, wants, desires. Define your characters the same way.

For example:
Khay is a bitter and resentful person. She is condescending, knowledgeable, proud, spiteful, elitist, and distrustful of others. She also has a softer side.

Versus

Khay is a refugee of war. She feels that it is unfair that she, a trained geneticist, is living in a camp with other, less qualified refugees, but still helps Alice as she flees the police despite the danger it presents for her. She wants to return to her job in the lab because she loved being able to be a part of something bigger, making scientific breakthroughs. She also wants revenge for her country being destroyed by war, and sometimes her frustration and anger is directed at people who don't deserve it.

Both of these paragraphs say the same thing about Khay's personnality. I think you can see that you get a way better understanding of who Khay is as a person with the second one.

Honestly, it's a lot about just writing out your story and putting them in scenarios? Before I actually got into writing the scripts and story, I had the same list of traits and interests and whatnot, and the same feeling as you. I think the more you kinda sit on the characters and develop the story as a whole, the more you kinda learn about them. I'm personally of the school that your characters are kind of their own people who develop as you write them and as you learn and grow yourself.

Maybe it would lead to OOC moments, but y'know a draft is a draft and no one has to see it lol but also it's your story and do what you like #cringeisdead

Either way, don't just "build" the character, set them loose into your world and let them run their course like a sims game lol

let's create a personality right now in this comment.

first we think a basis for the character it can be anything but let's start with one word: magic,

now we think of another unrelated word I will pick a mood, let's pick happiness,

the character is a joyful mage...

now we give an exception to that core emotion

.they are joyfull most of the time except when they see a dragon.

it can be anything.

now we give an explanation

dragons reminds them of when their whole vilage was burned down by a dragon and they were the only survivor.
they are joyfull because despite their trauma they decided to not let that weight them down
so they are fierce, strong willed, and never out of hope.

now we give some flaws.

they talk too much and can't foucus

a key is to with each layer add things not directly coraleted.

so far we have a strong willed joyfull fierce hopefull mage that get's sad when sees a dragon, talks too much and can't focus.

already we have an original compelling character, but that alone won't do for a main character we need to add more,

so lets do a complete backstory

they born in a simple vilage, raised by loving parents who were farmers unltil at the age of 8 a dragon atacked their parents fought to keep the character safe and sacrificed themselves with a smille, an smille that would be inprinted in the character's mind as an example of atituted toward adversity, the character survives but nothing is left of their vilage they decided to not let that put them down so they move on, and find a mage they become an aprentice to the mage and become skilled at nagic, their main goal with magic is bring their family back something that is said to be impossible except with the help of an artifact so they go an a jorney to get that.

and now not only we have a compelling character but also a basis for the story that is character driven.

it's not an exact science and a lot is up to your imagination but try to combine as much diferent ideas as possible and them jusfy them for the character and that is enough for a story I think.

The main thing is have a story to tell. The characters are secondary to the story. They are just there to make it interesting. So after you have your story, create personalities that will drive the story forward and make the reader want to watch them continue the story.

Usually I give a character a main personality trait which can be over exaggerated.

Like "Austin has anxiety." So in most situation that character trait will be his first reaction.

I then build off their likes and dislikes. A character's dislike should be what they feel strongest against and could be tied to their main character trait.

I think it's good to give your character at least one hobby or hyperfocus.

It might be worth also giving them a type of intelligence. Even if someone isn't good at school work, they have other areas they might excel in. It's a strength of your character you can build off of or have them set goals to succeed in.

It could be worth starting with tropes. A trope is not just a trait; it's a trait and a narrative. For instance, you can have a shy character, but the shy character who musters up the courage to break out of their shell vs the shy character who is saved from their loneliness by a manic pixie dream friend vs the shy character who is totally content staying that way are all different tropes.

If you have a list of traits, think about where you want to take them. Are you portraying the trait as positive or negative? Do you have some traits that are usually portrayed one way that you want to portray in the opposite way? (These are what make your characters interesting!) Once you have a few narratives attached to some traits, it'll be easier to find ways to fit them together with other traits, interests etc :]

I take a few tropes and build on them. And whenever I want to give them a trait I always ask "why?"

Like taking care of a plant, I set up a seed (The concept) and slowly develop it through events, seeing what would have affected them the most, like milestones in the way, tracking their most important experiences during childhood, their teenage years and adult years. Those elements help me hone their unique peculiarities and stop them from being cookie cut-outs of tropes.

A lot of it comes from life experience and people I have gotten to know, as well as my own personality traits. They tend to have both strengths and flaws I find endearing in a person. They are not necessarily traits I have as I personally like to separate myself from my characters as they aren't me. They are my works of art on their own.

I have the worse character development xD Nate is based on some aspects of myself, Matt is based on my best friend, Charlie has other aspects of me too and what I wished I was, Mike I just thought "he has to be angry but care for people in silence". Their likes and deslikes I started with the basics, and as I wrote they started to grow and have more of their own personality. So in the begining I knew Nate should be shy but impulsive and adddicted to games, Matt should be outgoing, caring and a gamer too. Charlie is silly and direct on what she wants, Mike is what I've said xD and liked to play videogame to pass the time. And then I developt them as I went on, based on those and a few more traits.

I work like @delladz said; I have the basics and let them be themselves. I always thought that my writing style was like I was watching them live and I'm just writing down what I saw. It works well because I make a slice of life, so I dont have to imagine great things like in a fantasy, I can just let them be in a day to day scenario and this on its own develops their personality. Because as a reader you will get to know them slowly, as do I.

My main characters hide their pains & not completely out about it. They act a little unusual on their own. I just never want them to clash (not this early) and be certain to bring slow suspense to the readers

I'm the worst at this. I start by working up some background and context for each character and then basically I just throw them into the story and sort of see what feels right for them. I think this actually adds to the joy I get from writing because my characters surprise me on the regular, so it's all part of the fun.

I have a friend who intricately plots everything and I keep trying to do that and my characters just keep doing their own thing anyway. This means I can never weave the kind of plots she does because I'm not in control of what happens after the characters start to assert themselves.

I tend to develop characters in relation to each other, and bearing in mind what kind of dynamic I want the main narrators (I write in third person limited) to have with each other.

For Blue Eagle, Cricket Prince, the initial core concept of the plot was this: a Han prince and a Mongolian prince make an alliance, even though on ordinary days they should want to kill each other.

So from there I thought, what kind of dynamic do I want? I felt that an aggressive relationship was too cliche, and so I began to think about the two of them as 'head before heart' characters.

Zhisen, steeped in the Imperial Court's politics, constantly tip-toeing around the executioner's block, naturally became a calculating politician with a sharp tongue.

Khojin, who spends most of his spare time alone under the endless sky of the steppe, with lots of time to reflect on himself and his life, became a more thoughtful man, whose sense of honour and morality are always in opposition with his direct (and bloody) involvement in warfare.

I decided that Zhisen and Khojin would be quite different to each other in how they behave and how others perceive them— Zhisen as a cold schemer and Khojin as an honourable warrior— but that in order to make a successful alliance, the way that they think had to be similar. And so they share some struggles with each other:
- a desire to escape their political responsibilities, in conflict with their ultimately dutiful personalities
- a complicated relationship with their (emperor) fathers
- a disdain for war, in conflict always with their direct planning of it
- loneliness (I mean, how many people around them could actually empathize with these problems?)

And that's how it all began!