Definition of Foreshadowing
The conclusion of the novel reveals that, despite widespread belief that Constance is guilty of the murders of her family members, it was actually Merricat who poisoned them. Her guilt is foreshadowed at various points in the novel, as she shows a persistent interest in poisonous substances. When speaking to Charles, for example, she delivers a thinly-veiled threat:
“The Amanita phalloides,” I said to him, “holds three different poisons. There is amanitin, which works slowly and is most potent. There is phalloidin, which acts at once, and there is phallin, which dissolves red corpuscles, although it is the least potent. The first symptoms do not appear until seven to twelve hours after eating, in some cases not before twenty-four or even forty hours. The symptoms begin with violent stomach pains, cold sweat, vomiting—”
“Listen,” Charles said. He put down his chicken. “You stop that,” he said.
Some time after the arrival of Charles to the Blackwood family home, Constance plays the harp for Charles, Merricat, and Uncle Julian. In her narration, Merricat uses one of her "words of protection," foreshadowing the disaster that soon befalls the Blackwood sisters:
Unlock with LitCharts A+That evening Constance played for us in the drawing room, the tall curve of her harp making shadows against our mother’s portrait and the soft notes falling into the air like petals. She played “Over the Sea to Skye” and “Flow Gently, Sweet Afton” and “I Saw a Lady,” and other songs our mother used to play, but I never remember that our mother’s fingers touched the strings so lightly with such a breath of melody. Uncle Julian kept himself awake, listening and dreaming [...]