Okay, let me start by saying that this is one of my favorite things in the world. This may become a multi post. ‘Kay? And if I go of into a tangent . . . I’m not sorry. *laughs nervously.*
Now that that’s out of the way, let’s begin.
To me, character building comes in two different aspects.
Them growing and learning. Maturing and developing, such as Tony Stark’s moral and personal development from the first Iron Man through to Infinity War.
How their journey has led them to new thought patterns or has changed the way they react or think. Like Doctor Strange. In the beginning of his story he is very selfish and greedy man who seems not to care for anyone but himself. At the end of the story, he actually cared enough to sacrifice himself, sort of, to save everyone. He still has cruel moments, but more things were added to his personality. Like sacrifice and love.
The other is the depth of the character. Knowing the small and big details. Such as my two characters Alison and William from ‘Murder Mystery and the Gingerbread Cookies.’ William is a coffee and tea connoisseur. Alison however can’t stand the taste of coffee or tea. And must dilute them both with cream and sugar until the taste has vanished into the background.
Those details may not seem like a big deal. But they can lend a hand in how you write your characters. Small things lend themselves for the big things. Making your characters seem more real. Less like ink on a page.
When I’m trying to get to know a character(s) I tend to do 30+ writing prompts. I go through Pinterest and search for writing prompts that remind me of the WIP/character(s) I’m working on.
Then I craft together the chosen ones into a list in a word doc or a journal, and I write!
I usually only choose one prompt per day and then by the end of a month, I’ve gotten to know my character(s) better! Which means that when I write them in their WIP, the complexities of their backgrounds can leak through. Like William’s disgust at Ali’s sugar habits. Or Tony Stark’s not liking to be handed things.
It’s small, yes. But it makes such a difference.
Well I’ve rambled on enough about this for today . . . But I’ll be back with more cause this is one of my favorite subjects 
