Building your character is like building a lego tower.
Can you tell I have 2 kids?
When you build a lego tower, you don’t know how complicated it will become until you’re in the process of building, of adding one block and then another block, ooh and then this short one, oh and then the really long one! Yes, sometimes you can plan it out before in your head, the basic design, but once you get to building, it’s fun to create.
When you build a character through the process of writing, you begin with one block from their past, and then another, and then another. As you write, you’ll likely think of more blocks interesting facts, tidbits, personality quirks to add based on their past, or whatever. The more you write, the more your character can come to life.
I realize this is not very sound engineering advice. Good thing I’m a writer 😀
I sincerely believe it does help significantly to fill out a character sheet of facts about your character, and even perhaps write out a chapter or two of pure backstory that won’t ever see the light of day.
But there is nothing like the actual process of sitting down and writing out scenes and dialogue. The act of putting your characters into their story and letting them run with it. You can write down all the character facts you want, but you can’t character build until you put that character into play and let him go and watch him react to situations you put him through.