Yes, sometimes you only learn why a character does something later in the book (or series). As for my writing process, I tend to get ideas and run with them. I outline as things come to mind, but have also written entire novels by the seat of my pants, not knowing what's going to happen until it does. It's a fun way to write, but it's helpful to know where the plot is going as I write, too. Regardless, my characters tend to take on a life of their own. ;) Thanks for reading!