The more I work on my novel, the more I get to know and like my cast of characters. My main character, Steve (the protagonist) has grown on me especially. He is the person who discovers the world of the novel along with the reader. One of the ways I've familiarised myself with him is to ask questions so that rather than the plot leading him along, his motivations and reactions create the story.
Bridget McNulty's article 5 Essential Questions to Ask When Writing Your Protagonist on the Fiction University website takes a similiar approach.