I need help refining a topic/ thesis statement for a Harry Potter research paper?

This is for a junior level college English course that has focused on the Harry Potter series all semester. I know that I want to write about the role of death within the series, and I have several sources discussing death in Harry Potter, however I need help refining my topic (narrowing it to something more specific) and coming up with a thesis, I'm not an English major and this is not one of my strengths. Help would be very much appreciated!