This is most likely a pathos type of rhetorical appeal. Pathos refers to an argument based on emotion. When this type of argument is presented, the speaker usually relies on appealing to the emotions of the audience. In this case, the author appeals to the emotions of the audience by describing the people who keep wolves as pets in very negative ways (self-centered, vain) and the wolves in positive terms that remind us of their wild nature.
Pathos means emotion and it is a way of convincing an audience of an argument by creating an emotional response to an impassioned plea or a convincing story.
Lyddie squealed with delight. Lyddie is distressed that Charlie looks so thin and that he hasn't grown much. Yet, she also cried because she was so happy to see him.
