what causes kino's hatred of the doctor to melt into fear

The doctor's newfound interest in Kino stems from a manipulative and dangerous greed. His visit to Kino reveals that he not only wishes to secure part of Kino's new fortune through the salary the doctor might receive for treatment but, as shown by the doctor's attempt to locate the pearl in Kino's hut, that he intends to steal the pearl. Steinbeck makes clear that the doctor does not visit Kino to cure his son; in fact, he indicates that the doctor's treatment of Coyotito might even be superfluous.

After the doctor leaves again, Juana asks Kino whom he fears, and he answers Œeveryone.' That night, Kino thinks that he hears noises in his hut. He grabs his knife and strikes out in the dark. The person scurries out. Juana tells Kino that the pearl is evil and will destroy them. She tells him to throw it away or break it, for it will destroy them. Kino says that the pearl is their one chance, and that the next morning they will sell the pearl.