This character, based upon
a real person, Camille Delcommne, is the ultimate villain of the plot.
He is directly or indirectly to blame for all the disorder, waste, cruelty,
and neglect that curses all three stations. He is in charge of everything.
Marlow suggests that the manager arranged to wreck Marlow's steamboat in
order to delay sending help to Kurtz. He also deliberately prevents rivets
from coming up the coast to complete the steamboat's repairs.
At the manager's command,
a native black boy is beaten unmercifully for a fire which burnd up a shed
full of "trash." (The boy is probably innocent.) The manager's conversation
with his uncle reveals the full, treacherous nature of both men. His physical
appearance is ordinary; his talents are few. Excellent health gives him
an advantage over other men. He seems to "have no entrails" and has been
in the Congo for nine years. His blue eyes look remarkably cold, and his
look can fall on a man "like an axe-blow."
http://www.acsu.buffalo.edu/~csicseri/chara03.html