....

        Despite his title, he is a man who seemingly makes no bricks; instead, he acts as the manager's secretary, and he is responsible for a good deal of the plot's entangling elements. For example:

    - He reveals the reason why the manager hates Marlow

    - He shows Marlow the painting which Kurtz left at the Central Station (one of the important symbols of the book).

    - He reveals the reason why the manager hates Kurtz

    - He unwillingly and indirectly lets Marlow know that the delay in getting rivets is intentional

    - He lets Marlow know that the white men at the Central Station identify Marlow with Kurtz, as members of the "new gang of virtue."

http://www.acsu.buffalo.edu/~csicseri/chara04.html