At the start of the novel an unnamed character introduces the frame of the story: evening spent aboard the Nellie. Through him we meet our second/ main narrator Marlow who tells most of the story from his point of view.
Hearing Marlow’s narration on his view of the story can make readers see things differently and it may have more of an affective on people than a narrator who hadn’t had personal experience with this exploration.
The point for the peripheral narrator is to make little side comments on Marlow’s voice because Marlow is human and his emotions can get the best of him while this narrator gives us fact to go with his emotions. Therefore, the main reason for a nameless character is to give us a greater opportunity for more commentary, more connections, and more flexing of Conrad’s literary muscles. The frame of the story breaks the trip down for us to make it easier to understand and comprehend.