Philosophizing
The first-person narrator is musing over memories of her mother and asserts that one of her favorite quotes comes courtesy of her. "You’ll never be able to find yourself if you’re lost in someone else.” It is a literal warning couched in metaphor about the danger of relying too much upon someone else to give your own life meaning. It is also a thematic concern prevalent throughout the narrative.
Revelation
One of the key metaphors expressed in the book comes at a point of revelation. "Why didn’t you tell me that the foundation you taught me to stand on is made from quicksand?” That this quote is actually italicized in the book indicates that this isn't a quote that is expressed, but only thought. The foundation that turns out to be made of quicksand is elegant, but the metaphor is simple. It is a description of a lie.
Gift Box
Much of the use of metaphorical language is devoted to philosophical musing. "A body is simply a package for the true gifts inside." This is another example of thoughts not expressed verbally. It appears in a letter to another person. The upshot being that the person the letter is sent to is identified as a package stuffed with gifts.
Scars
One of the first-person narrators is a young woman named Fallon who suffers the scars of being badly burned. She observes how her "scars feel like stretched velvet, and it would be normal to be as revolted by their feel as I am by their appearance. But instead, I actually like the way they feel." Velvet is one of the rarest worn materials, usually saved for special occasions. This confession speaks to the emotional dimension of that concept of rarity more than the actual texture of the scars.
Love
"I’m in love with her. Like, really in love with her. Crippling, debilitating, paralyzing love." This is more than a simple admission of feelings. It is a metaphorical menu that reveals the speaker's psychological construction of love as a concept. It is something that controls the very mechanics of forward movement.