In Joseph Conrad's novella "The Heart of Darkness", there are two main characters that are meant to complement one another, Charles Marlow, and a man referred to simply as Kurtz.
Marlow is a gruff sort of fellow who appears not to care about anyone but himself. However, he shows a distaste for the way the the Natives are treated. In one particular instance, he watches a group of chained slaves pass by him and remarks upon it to himself, "All their meagre breasts panted together, the violently dilated nostrils quivered, the eyes stared stonily uphill. They passed me within six inches, without a glance, with that complete, deathlike indifference of unhappy savages" (Greenblatt et al, 2006).
Most colonists would have looked away from the slaves, and not even thought of them as men, but Marlow mused upon the state of them. His thoughts eventually culminated to a grandoise conclusion that pretty much summed up the moral challenges in the story: "I've seen the devil of violence, and the devil of greed, and the devil of hot desire; but, by all the stars! these were strong, lusty, red-eyed devils, that swayed and drove men -- men, I tell you," (Greenblatt et al, 2006). The men that led the slaves past Marlow were what he considered to be 'devils'.
Kurtz is an infamous man that Marlow meets after only hearing rumors about him. Marlow says of him, "I would become acquainted with a flabby, pretending, weak-eyed devil of a rapacious and pitiless folly. How insidious he could be, too," (Greenblatt et al, 2006).
Marlow was not a perfect character, and neither was Kurtz, just as no one person is perfect. Every person has the potential for great evil, even if they are creative, kind, and articulate like Kurtz is. Marlow is more of the neutral man who witnesses all the wrongs being committed, internally condemns them, but can do nothing to stop them. Kurtz is a man who knows that his lust and greed for ivory have gone too far, but he still went goes on with it. Only on his deathbed does he grasp the scope of the life he has wrought, and the pain he has brought upon others.
Greenblatt, S., et al. (Eds.) (2006). The Norton anthology of English literature (8th ed., Vol.2). New York, NY: W. W. Norton & Company, Inc.