In standard literary fiction, the “plot” (a fairly vague term signifying the movement of the action forward) and the characters (the fictive “human” creations of the author based on normative psychological traits; not to be confused with “moral character”) commingle in what is know as the “mise-en-scene”—the social, physical, temporal, geographical “real” world. The characters act in this world according to their psychological and social positions, and their acts (speech, physical actions, thoughts, etc.) reveal their personalities, the persona they bring to the challenges, rules, and possibilities of the mise-en-scene they find themselves in. In the process of the characters “living” in the mise-en-scene, the plot moves forward by cause-effect principles built into physical and social “laws”: they change the world around them and are changed by the world around them. The relationship of plot to character, then, is a mutual dynamic that the reader follows to its resolution. Example: Capt. Ahab, a fictive character, in the mise-en-scene of 19th century New England whaling commercial activity, gathers a crew of characters (each of which has its own traits—Queequeeg, Ishmael, etc.) and sets out to make a living whaling. As the plot moves forward, the reader discovers that one of Capt. Ahab’s personality traits is a dominant drive toward his goal, and the reader discovers that one of the most powerful features of the whaling mise-en-scene is a white whale, Moby Dick. The plot, then, is driven to its conclusion by the battle between these two opposing forces.
Simple put the character drives the plot.