Who is Joaquim Cutinho from The Viceroy of Ouidah and what is their importance?

Joaquim Cutinho is the son of a wealthy Brazilian farmer and businessman. When Francisco goes to work for the Cutinho family, Joaquim meets him and the two young men become friends. Joaquim brings Francisco to stay with him at the family plantation home, but then he tells Francisco it is time to leave after Joaquim's father becomes ill. This is an early sign that Joaquim will mistreat Francisco, which he does after they meet again and Joaquim's business syndicate sends Francisco to Dahomey, which they know is ruled by a dangerous king. As the novel proceeds, Joaquim's treatment of Francisco becomes increasingly manipulative and unethical.