Consider Part I ¶ 62, 63, and 64, starting with:
I would not have gone so far as to fight for Kurtz, but I went for him near enough to a lie. You know I hate, detest, and can’t bear a lie, not because I am straighter than the rest of us, but simply because it appalls me. There is a taint of death, a flavour of mortality in lies—which is exactly what I hate and detest in the world—what I want to forget. It makes me miserable and sick, like biting something rotten would do.
Consider the following three questions and answer one of them:
What lie does Marlow tell for Kurtz, and why does he tell it? How does Marlow become entangled in a lie when he signs on as a steamboat captain in the Congo?
What is the nature of his attachment toward—loyalty for—Kurtz? Just a preference for hot-running devils?
Can you find any clue to the effects—physical & spiritual—of Marlow's experience in the Congo in Narrator One’s description of him?