Kurtz has rather unique role in novel. Describe what those roles are in terms of the structure of novel. How do other characters relate to them and what is their position in the stories?

Kurtz himself is an uncertain figure, ruled as he is by two separate impulses, the noble and the destructive. At the beginning of the novella, the reader perceives that the former is his dominant (or only) characteristic. But with vicious scrawlings on his manuscript and his ruthlessness in extracting ivory from the land, Kurtz proves himself the latter. Marlow’s adherence to Kurtz until the end confuses the matter; one could judge him one way or the other. The idea of "darkness" expresses the theme of uncertainty in the novella.