Crafting Real Characters

When you think about the books, TV shows, and movies you love the most, what stands out? What makes a story memorable, believable, or addicting?
For me, it's the characters. They are our portal into the story, the lens through which we experience everything, so it's important that characters are unique, believable, and memorable.
Sometimes when we write, the players come to us as fully-formed brings in our minds, but sometimes they need a bit of work to flesh out.
This is where outlining and drafting come into play, and exploring what makes our characters tick. The basics come to light in the writing: motivation, conflict, strengths, flaws, etc. But I've found it incredibly helpful to do some side work to figure out more specific details and personality elements that might not come about in the book.
I've created a character questionnaire for this purpose. It's a series of questions to help you flesh out a character and solidify them so their decisions feel authentic.
I'm linking it below, so give it a try!
I want to know: how do you outline your characters? Which personality traits jump out to you as both a writer and a reader? Leave your thoughts in the comments!