This excerpt shows a tone of admiration through all of the words the narrator uses to describe the subject. He says they are "fierce as a dog" and "cunning as a savage". Fierce and cunning are two words that seem admirable to the narrator. The word "rebuilding" at the end also shows admiration, as the subject keeps rebuilding after things have been broken down.
Juxtaposition is meant to show a contrasting effect. Throughout the passage, the narrator shows that he is constantly surrounded by a crowd of people. However, he likes to spend his time alone and by himself.