Which character is Buck’s main rival in the beginning?

In the beginning of "The Call of the Wild," Buck's main rival is Spitz. Spitz is the lead dog of Thornton's sled team, and as a strong and experienced dog, he embodies the challenges and struggles Buck faces as he adapts to life in the harsh wilderness. Their rivalry is characterized by Spitz's dominance and authority within the pack, which creates a tense relationship with Buck.

As Buck experiences the brutal realities of his new environment, he begins to assert himself and challenge Spitz's leadership. This rivalry serves as a catalyst for Buck’s transformation, pushing him to tap into his primal instincts and fighting spirit. The conflict between Buck and Spitz represents not only a personal struggle for dominance but also Buck's journey of survival and adaptation in a setting where only the strongest thrive. Thus, Spitz is integral to the plot as Buck evolves from a domesticated pet to a fierce survivor shaped by the wild.