It started out tragic and now it's lightening up

Wolfe: Murder started out with the protagonist in misery, self-doubt, and pain. As he goes through the story, he's finding hope and some fun in life so his demeanor is changing from dour to lighter with some smiles and quips. Is this realistic? Maybe it's what's supposed to happen. I just have to keep putting words on the screen and see that happens. How to maintain some control?