If you're having trouble getting into your protagonist's head, try this: "Simple Tricks for Authors to Get Inside a Character's Head"   and see if that helps you to get to answering the questions for how their life has changed throughout the story you have planned. It's hard to figure out what's changed if you can't figure out how your character really feels and talks in the first place.

"Whoever fights monsters should see to it that in the process he does not become a monster. And when you look long into the abyss, the abyss also looks into you."-Nietzsche