What role does the harlequin have in Heart of Darkness?
The Harlequin/Russian trader acts as a means of characterizing Kurtz. We gain most of our information about Kurtz through him.
The harlequin gives us a rather warped view of Kurtz. He speaks of him with awe and reverence. "Don't you talk with Mr. Kurtz?", Marlow asks him. "'You don't talk with a man like that-- you listen to him', he exclaimed with severe exaltation." He mentions that Kurtz speaks beautifully on subjects, offering love as an example. Paradoxically, he also mentions that Kurtz stole his ivory at gunpoint and killed and plundered in African villages.
The Russian man seems also to represent an immature, ignorant exaltation of imperialism and colonization as a glorious and honorable undertaking. He is a young, white man. Marlow say he is ruled by an, "absolutely pure, uncalculating, unpractical spirit of adventure", and that dotes on Kurtz because he has not thought it through. And maybe its true. The Russian sees the brutality and madness of the colonizing Kurtz and still holds fast to him, nearly worshiping him, his intelligence, his voice, his stories.
He has a sort of childlike innocence about him, and though he does not brutalize the African like Kurt, he is still a willing-- and enthusiastic-- cog in this system.
The harlequin is a young Russian man, who dresses in colorful clothing and is considered one of Kurtz's disciples. When Marlow initially arrives at the Inner Station, he is immediately introduced to the harlequin, who gives Marlow insight into Kurtz's character. Despite the fact that Kurtz threatened to kill him, the harlequin offers nothing but praise for the enigmatic leader of the station. The harlequin also tells Marlow about Kurtz's enticing, persuasive voice and mentions that Kurtz has enlarged his mind. The main function of the harlequin is to characterize Kurtz as an enigmatic, wise individual, who has an extraordinary ability to captivate his audience. There are also several motifs associated with harlequin's character, which include his colorful patches and his comment about Kurtz enlarging his mind. The colored patches on his jacket correspond to the colorful map Marlow initially examines before his journey, and the harlequin's comment about Kurtz enlarging his mind relates to the doctor's statement concerning his experiment with men returning from foreign expeditions. Overall, the harlequin provides valuable insight into Kurtz's character and serves as a conduit of information for Marlow.
The harlequin aids in the characterization of Kurtz. Without him, Conrad would have had to find another way for Marlow to come to a fuller understanding of Kurtz's psyche before he meets him himself. The fact that the harlequin has become a disciple of Kurtz more deeply informs Marlow that Kurtz is a Svengali of sorts, a figure who seduces and manipulates those who enter his orbit.
The harlequin, known traditionally as a "fool," also embodies the proverbial idea that "fools rush in where angels fear to tread," or that in one of life's often observed ironies, fools survive. In some ways, his youth and susceptibility function as a foil to Kurtz's age and craftiness. Marlow's observation of the harlequin is that he is young, and readers understand that his youth is at least partly responsible for his inability to recognize Kurtz as the megalomaniac he has allowed himself to become.
The harlequin, or Russian, gives Marlow with a great deal of information about Kurtz, the he would not have had without the Russian's presence. The Russian most important information is that Kurtz is adored by the African tribe that follows him, that he once nearly killed the Russian for his small supply of ivory, and that it was Kurtz who ordered the attack on the steamer to scare them away. He is also a person who is unconditionally loyal to Kurtz, even saying "This man [Kurtz] enlarged my mind.