How does the relationship between Buck and John Thornton deepen during the course of the story?

The relationship between Buck and John Thornton deepens significantly as the story progresses, primarily characterized by a bond of love and mutual respect. Upon meeting Thornton, Buck experiences a nurturing connection that contrasts with the harsh treatment he faced from previous owners. Thornton provides Buck with kindness, compassion, and admiration, which allows Buck to thrive both physically and emotionally.

This deepening bond is illustrated through various moments of loyalty and sacrifice. Buck’s willingness to save Thornton from danger and his fierce protective instincts showcase the emotional depth of their relationship. In return, Thornton recognizes Buck's worth and abilities, valuing him not just as a work animal but as a cherished companion. Their connection transcends mere utility; it becomes a profound partnership rooted in mutual appreciation and affection, exemplifying the themes of loyalty and the importance of connection in the face of adversity.