How we cite our quotes: (Chapter.Paragraph)
Quote #4
I wasn't sure of my own strength. If I could press a button right now, here in my room, that would take me straight to the Fields, would I be able to refuse? I didn't know. (9.39)
For all that Nikki is aware that she's being super-principled about the whole do-the-right-thing aspect of her Return, she's not sure how much temptation she can resist. When Cole shows her a glimpse of the Fields—the heavenly counterpart to the hell that is the Tunnels—it's so lovely and ideal that she's tempted to accompany Cole there. But it'd mean preying on others, so she eventually finds the strength to refuse it.
Quote #5
With my lips against his, I reached a conclusion I'd been trying to avoid: the easy path in this whole mess would be to go with Cole, and I couldn't let myself make the easy choice. I had to make the right choice. (9.65)
Cole is apparently a pretty good kisser, but even that isn't enough to keep Nikki from realizing that anything between them wouldn't be real. Letting Cole feed off her emotions and then make her an Everliving would be taking the easy path out, rather than making the choice to do the right thing. And once Nikki has this realization, her principles force her to come to terms with the fact that doing the right thing is what matters most.
Quote #6
I thought about Jack […] And then I realized the truth. I left him once on the other side of the century. I couldn't leave him of my own volition ever again. The Tunnels were going to have to take me. I didn't have what it took to go early. (14.75)
When Nikki is so full of despair that she contemplates consuming one of Cole's hairs in order to go to the Tunnels before her Return is up, she has yet another revelation about her principles. She's strong and stubborn… but not enough to shorten her Return in order to prevent causing others pain. This is the point where Nikki realizes that she does have a horse in this race, and that horse is named Jack.