Conrad's use of two narrators in Heart of Darknessreinforces several of the novella's themes. The bulk of the narrative is told by Charlie Marlow about his experiences in traveling up the Congo River in search of Kurtz. Marlow retells his adventure while aboard a ship, the Nellie, in the mouth of the Thames River waiting for the tide to carry them out to sea. The Nellie and Marlow are introduced to the reader at the very beginning of the novella by an unnamed narrator. Both Marlow and this unnamed narrator are not entirely reliable in their accounts of events, both leave out considerable details which beg the reader to become more involved in constructing the meaning of both narratives. Even the interpretations of events of each of these narrators is somewhat suspect--very little can be taken as fact.
All of this supports one of the central themes of the novella: the ambiguous nature of truth, evil, and morality. By using two narrators, we are exposed to differing perspectives on the same basic concept--the journey into a "heart of darkness" within the human soul--and are left to come to our own conclusions about its meaning and significance.
Joseph Conrad in his narrative "the heart of darkness",uses two narrators.The first one being a non descriptive character and the second one being Marlow himself.He uses both the forms of narrators to create a frame for the narrative and also to create a sense of mystery and suspense.He presents the first narrator as someone who even the said listeners might listen and accept and the second narrator by suggesting that there is something extraordinary in the past of the hero that makes him unlike other men.