why will white fang not make friends with dick?

"All he asked of other dogs was to be let alone. His whole life he had kept aloof from his kind, and he still desired to keep aloof. Dick's overtures bothered him, so he snarled Dick away. In the north he had learned the lesson that he must let the master's dogs alone, and he did not forget that lesson now. But he insisted on his own privacy and self-seclusion..."