which aspect of the world most fascinates the narrator of "The Book Thief"?

It is both the survivors, the ones who are left when the dead leave, as well as the colours of the world.

The first is directly stated as follows;
"Still, it’s possible that you might be asking, why does he even need a vacation? What does he
need distraction from?

Which brings me to my next point.

It’s the leftover humans.

The survivors.

They’re the ones I can’t stand to look at, although on many occasions I still fail. I deliberately
seek out the colors to keep my mind off them, but now and then, I witness the ones who are
left behind, crumbling among the jigsaw puzzle of realization, despair, and surprise. They
have punctured hearts. They have beaten lungs."


And is repeated again in the first chapter;
"I studied the blinding, white-snow sky who stood at the window of the moving train. I
practically inhaled it, but still, I wavered. I buckled—I became interested. In the girl.
Curiosity got the better of me, and I resigned myself to stay as long as my schedule allowed,
and I watched."

The colours are also stated as something he watches in the other portion of his vacation;

"The question is, what color will everything be at that moment when I come for you? What
will the sky be saying?
Personally, I like a chocolate-colored sky. Dark, dark chocolate. People say it suits me. I do,
however, try to enjoy every color I see—the whole spectrum. A billion or so flavors, none of
them quite the same, and a sky to slowly suck on. It takes the edge off the stress. It helps me
relax."