Which comes first, the character or the plot?
Plot is "What happens?" The character is "who it happens to."
What happens is important, but the character should drive the action. If the character is an individual, then the action will happen in an individual kind of way. Writers call that Character-Driven plot
Stories where plot comes out of character, rather than the opposite are usually the best and the ones that remain with you. There are writers who think of really ingenious plot lines (Donald Westlake and Agatha Christie come to mind) and write entertaining books or stories, but the main characters in those stories are often sort of “cardboard.”
Dortmunder is always Dortmunder in the same way that John Wayne is John Wayne. Other than the fact he has terrible luck, we don’t know (or care) a lot about Dortmunder. What outlandish ploy he’ll think of next and what disaster will result, is the important thing. Poirot is always Poirot with his little mostache and his “little gray cells” but, again, we don’t much care about him as a man. Solving the murder is the thing.
Contrast Poirot or Dortmunder with Sharyn McCrumb’s psychic, wise, mountain woman, Nora Bonesteel. Nora is a character I’m always willing to spend time with. In a book like She Walks These Hills, Nora is equally as important as the plot, and a year after reading it you may have forgotten the plot, but you will remember Nora. Anyone who writes character-driven stories is doubly blessed.