I tend to build my characters around a specific emotional moment that stay with me from different books/movies.
Kyla is very much based on the book The Mascot about a Jewish boy in WWII and dealing with watching all the people of his town die.
Cell is based partially on my own childhood, with a small mixture of various other works.
Selias is based off of a single scene in an old French film I don't even remember the name of. I will never forget that scene though.
I like to work with others to tell a good story.
I also tend to think that outside of the story you tell you have no control over your works. If I end a story with open ends, I have given that reality to the readers. It is up to them what they believe happened. Once I share a story with the world it isn't just mine anymore.