How we cite our quotes: (Chapter.Paragraph)
Quote #1
Before he could think better of it, Nick swiped him upside the head with his backpack as hard as he could. (1.78)
When Nick is stressed out or feels threatened, his first reaction is to turn violent. This will become a problem for him later on. He might have an easier time resisting the dark side if he were more levelheaded.
Quote #2
One day…one day he was going to get out of this hellhole. Even if he had to kill someone to do it. (1.194)
Nick is pretty desperate to change his lifestyle. Early on, it feels like this could be foreshadowing—like, Nick might have to kill someone to escape. But it turns out that he doesn't, so this line is simply characterizing Nick as a character who has no problem with violence if it acts as a means to an end.
Quote #3
Nick felt the color drain from his face. This couldn't be happening. They were mugging two tourists? (1.256)
Nick has violent tendencies, but he rationalizes these tendencies by only being violent toward people he thinks deserves it. These two tourists are innocent, so Nick is aghast that his friends attack them—and so he defends the tourists.