“Why, I haven’t got an enemy in the world.” 

Linnet makes this statement early in the novel, and it demonstrates her naïveté about others’ true feelings toward her. As Mrs. Allerton later suggests, Linnet does in fact appear to be “fey,” as she feels the kind of impossible happiness that comes before a severe reversal of fortune. As the novel progresses, she comes to feel quite differently, proclaiming that it feels as if everyone hates her. 

“I shall die if I can’t marry him! I shall die! I shall die! I shall die…” 

Jackie’s passionate outburst expresses her excessive love for Simon, which leads her to take part in the murderous plot against Linnet; it also foreshadows her death at the end of the novel and illustrates the novel’s theme of the danger of loving too much. 

“She cares too much, that little one…[i]t is not safe. No, it is not safe.” 

From his very first contact with Jackie, Poirot senses that her fate will be an unhappy one. There is evidently something about Jackie’s behavior with Simon that suggests to Poirot that her love is unhinged in some way. The phrase “that little one” signals Poirot’s sympathy for Jackie and his desire to protect her from the moral danger that surrounds her.