Talking to you is like traveling through time.
This quote clearly reveals Joe’s adoration of Beck as he believes that simply speaking to her is the equivalent of traveling through time and matter. Not only this, but Joe compares his dialect with Beck with the universal concept of time, as though he could spend all eternity speaking to her. This is signifying the start of a long-term obsession that takes hold throughout the book.
Your lips were made for mine, Beck. You are the reason I have a mouth, a heart.
Joe’s obsessive nature comes to the forefront here as he is carefully using possessive personal pronouns such as “you” and “I” which demonstrates his sense of power and control over Beck - there seems to be a strong sense of ownership and possession here. Rather than expressing that directly, Joe manages to successfully intertwine his power with romanticism, where he compares the being of Beck with his “mouth” and “heart” – two features that lovers merge together to express their love for one another.
When I'm nervous, I get nasty. It's a problem.
Here, Joe’s “nasty” and obsessive nature comes to light as it is revealed that he has a dark side. Joe’s nature is claimed to be a "problem” as though his obsessiveness with Beck is undying in itself, a habit that refuses to change. His supposed “nast[iness]” is foreshadowed later on in the novel when he murders her.