Why does he lose his genial, playful, puppyish side

This brings about a change in the young puppy - he is forced to abandoned much of his "childhood," he becomes a solitary figure in camp. He begins to develop his intellect, his cunning and his skills. One day, while being chased, White Fang deliberately leads Lip-Lip past Kiche, who is able to deal a great deal of revenge for her son.