How we cite our quotes: (Chapter. Paragraph)
Quote #16
A swift rigidity fell on all of them as James lurched one step forward into a crouch. Edward bared his teeth, crouching in defense, a feral snarl ripping from his throat. It was nothing like the playful sounds I'd heard from him this morning; it was the single most menacing thing I had ever heard, and chills ran from the crown of my head to the back of my heels. (18.27)
James and Edward are exhibiting their normal, fighting behavior.
Quote #17
[Alice to Bella:] "We're also like sharks in a way. Once we taste the blood, or even smell it for that matter, it becomes very hard to keep from feeding. Sometimes impossible. So you see, to actually bite someone, to taste the blood, it would begin the frenzy. It's difficult on both sides – the bloodlust on the one hand, the awful pain on the other." (20.88)
Alice explains what happens when a vampire tastes blood. She likens it to a shark feeding frenzy. She presents vampires' reaction to blood as natural, rather than evil.