what method of portraying did the author use?

Juana is practical and reflective; she symbolizes domestic happiness and provides balance for what becomes Kino's (her husband's) coming greed. This is made apparent in her attempt to cast off the pearl for which she receives a beating from her husband.

The doctor is arrogant, greedy, and condescending, and his character portrays oppression. The doctor doesn't care about the natives, only the money they provide. He, like other colonists is there because he's greedy, not because he's a compassionate man. This is evident in his refusal to treat Coyotito without collecting his fee first.

Lastly, we have Kino. He loves his family, exhibits loyalty to his people; keeps the traditions of his village, and is an extremely hard worker. He hates the colonists oppression of his people. He is also very smart and has a close relationship with nature.

Kino's discovery of the pearl changes him. He goes from the innocent fisherman to being corrupt and disillusioned by greed. The pearl makes turns his eyes from his own culture and toward the way of the colonists. His newfound greed affects his 'oneness' with nature and his 'oneness' with his family. Kino exemplifies the opinion that sometimes good things can make a bad end.