Kino and Juana are spiritual and superstitious. This novella opens by saying it is a parable about dualities, particularly between good and evil. Kino thinks of things in terms of songs: the pleasant Song of the Family and the foreboding Song of Evil, characterized first by the scorpion. When the scorpion approaches the baby, Juana tries using ancient and religious prayers:
Under her breath Juana repeated an ancient magic to guard against such evil, and on top of that she muttered a Hail Mary between clenched teeth. (Chapter 1)
Although Kino is a man of action, Juana is also assertive and strong. She lives simply but does not necessarily limit herself to the role of a subservient wife:
She, who was obedient and respectful and cheerful and patient, could bear physical pain with hardly a cry. She could stand fatigue and hunger almost better than Kino himself. In the canoe she was like a strong man. (Chapter 1)
She is also the one who suggests going to the doctor since he will not come to them. Juana shows more wisdom and intuition than Kino. She realizes the pearl will bring nothing but trouble. Kino is convinced otherwise and resorts to striking her when she tries to get rid of it.
Kino loves his family and is devoted and determined but he is also stubborn. Juana is the voice of reason in their family. When Kino says "I'm a man" to Juana,
It meant that Kino would drive his strength against a mountain and plunge his strength against the sea. Juana, in her woman's soul, knew that the mountain would stand while the man broke himself; that the sea would surge while the man drowned in it. And yet it was this thing that made him a man, half insane and half god, and Juana had need of a man; she could not live without a man. (Chapter 5)
But Juana could also command authority with her own reason and womanhood, and override Kino's stubborn determination:
Sometimes the quality of woman, the reason, the caution, the sense of preservation, could cut through Kino's manness and save them. (Chapter 5)
Kino and Juana are dedicated to each other from the start. But by the end of the novella, despite their tragedy or maybe because of it, they were more like equals than before:
The two came from the rutted country road into the city, and they were not walking in single file, Kino ahead and Juana behind, as usual, but side by side.