Quote 1
"Did you win?"
Luce laughed a sad, self-effacing laugh and shook her head. "Far from it."
Daniel pursed his lips. "But you were always…"
"I was always what?"
"I mean, you look like you might be a good swimmer," He shrugged. "That's all." (6.79-83)
This quote's more about an actual loss, rather than an emotional one. The important note here isn't about Luce winning or losing the race, but about Daniel's expectation that she would win. Just another moment when he gives away something that maybe indicates he knows more about her than he's letting on.
Quote 2
"I know cam gave you that gold necklace, too," Daniel said.
Luce hadn't thought about that since Cam had forced it onto her at the bar. She couldn't believe that was only yesterday. The thought of wearing it made her feel sick. She didn't even know where the necklace was—and she didn't want to. (20.72-73)
Although it seems a little anticlimactic to go from talking about the end of the world to talking about a missing necklace, this detail is important. Luce's attention to detail dwindles when she stops caring about things, and the fact that she lost Cam's necklace solidifies that any feelings she had for him really were entirely superficial. She isn't ever going back. It's now 100% Luniel. Or…Danuce?
Quote 3
"Warm milk with a spoonful of treacle," he murmured sadly, his back still to her. Then he added sadly, "It helps you sleep." (Prologue. 17)
How does Daniel know this? Oh, yeah—he remembers it from one (or several) of Luce's past lives. Does Luce pick up on this? Nah. She wouldn't be a YA heroine if she did.
Quote 4
"Did you win?"
Luce laughed a sad, self-effacing laugh and shook her head. "Far from it."
Daniel pursed his lips. "But you were always…"
"I was always what?"
"I mean, you look like you might be a good swimmer," He shrugged. "That's all." (6.79-83)
So Daniel's memories of Luce are even more all-encompassing than he lets on, but all of his thoughts are self-censored because he knows Luce incredibly well yet can't tell her that. He feels he is forced to push her away.
Quote 5
"I'm trying to say…I guess you could say I'm damned too, Luce. I've been damned for a long, long time." He spoke as if the words tasted bitter. "I made a choice, once, a choice that I believed in—that I still believe in…" (16.132)q
At least Daniel is good about sticking to his principles. Whether the choice he made was ultimately worth the price he paid for it is neither here nor there, but by calling himself damned, he indicates that he feels he needs to be redeemed, too. Maybe he hopes that by telling Luce this, she might begin to believe him.
Quote 6
"Warm milk with a spoonful of treacle," he murmured sadly, his back still to her. Then he added sadly, "It helps you sleep." (Prologue. 17)
Here we see Daniel (not yet named) showing how much he cares for Luce (also not yet named, since we're in Prologue Land)—and how much he remembers about her character. Learning and remembering someone's eating habits is an intimate thing, and Daniel's concern for Luce's sleeplessness, paired with his wish to help her fall asleep, is especially telling: it suggests that he knows a great deal about her and cares for her a lot. It's also the only instance in the story when Daniel and food are connected; we usually Cam and food connected instead. Basically, Cam + food = potential danger, while Daniel + food = comfort and safety.