“What a weird thing to grow up with, though, huh? Knowing how easily you could’ve been the wrong twin.” 

Ezra here refers to the airport attendant’s story about his twin having been absorbed in the womb. This idea of the “wrong twin” will echo throughout the novel, as Ellery struggles to reckon with her aunt’s disappearance and her own sense that she is “the wrong twin.” The final revelation of the book—that Peter intended to murder Sadie, not Sarah—drives home just how meaningful this idea is for Ellery.

“I became Declan Kelly’s brother before I got a chance to be anything else, and sometimes it feels like that’s all I’ll ever be.” 

Malcolm lives in Declan’s shadow, both in the town and in his own self-concept. Declan’s reputation makes Malcolm into an outcast, but the real struggle for Malcolm will be learning to understand and connect with his brother as he faces his own time in the spotlight.

“He and Sadie are so similar sometimes, so blissfully optimistic, that it’s impossible to say what you really think around them. When I used to try, Sadie would sigh and say, Don’t be such an Eeyore, Ellery. Once—only once—she’d added under her breath, You’re just like Sarah. Then pretended not to hear me when I asked her to repeat what she’d said.” 

Central to Ellery’s character is her struggle with her mother, and here, the reader is shown that it’s rooted in Ellery’s similarity to her missing aunt. Sadie’s free-spirit attitude is a defense mechanism against the tragedy she’s faced, and her seeing so much of Sarah in Ellery is a sore point for them both.