Throughout the story, Buck is very ambitious and determined to be the leader of the team. His ambition causes tension between he and Spitz, the former leader. Buck goes from being a very domesticated dog, to being a killer. "Buck stood and looked on, the successful champion, the dominant primordial beast who had made his kill and found it good." (Page 22)
Buck's ambitions are able to be fulfilled by his ability to fight. Francois and Perrault constantly comment on Buck's aggression toward Spitz. "'Eh? Wot I say? I spik true w'en I say dat Buck two devils.' This was Francois's speech next morning when he found Spitz missing and Buck covered with wounds." Throughout the book, Buck is slowly found to be a force of nature.
Buck's loyalty and love for John Thornton pushes him to achieve incredible feats. Unlike his former masters, John Thornton shows Buck respect and true love. This makes Buck feel the need to impress him. "His whole body was gathered compactly together in the tremendous effort, the muscles writhing and knotting like living things under the silky fur." (Page 44) "The sled swayed and trembled, half-started forward." (Page 44) Buck pulled a thousand pound sled, just because John Thornton told him to. This shows Buck has incredible love for his master.
Towards the end of...