In a moment of dramatic irony in Book 2, Bigger eats dinner with the Dalton family just as Mrs. Dalton receives Bigger's fake ransom letter. No one in the kitchen but Bigger knows the letter's real origin. Bigger reacts to this instance of dramatic irony with great fear. He feels the winds of fate swirling ever closer around him:
He was tensely eager to stay and see how it would all end, even if that end swallowed him in blackness. He felt that he was living upon a high pinnacle where bracing winds whipped about him.
Bigger's reaction to this dramatic irony is entirely new. Over the course of Book 2 up to this point, Bigger has felt a sense of freedom, as he feels that his life is no longer under the control of others, and that he can make his own decisions. But in this moment of dramatic irony, Bigger finds that he has recreated for himself another system that controls his life, even after he felt that he has just emerged from another one. Now, Bigger's life is entirely controlled by avoiding arrest and planning further crimes. Bigger's reactions to moments of dramatic irony, when he knows the real circumstances of Mary's death while no one else does, show his change of worldview. Earlier in Book 2, Bigger felt a freedom and possibility from his unique knowledge of the murder. Now, he feels constrained and isolated.
In Book 2, Bigger stops at the soda fountain on his way from his family's house to the Daltons' house, planning to check on the state of Mary's corpse in the furnace. At the soda fountain, Bigger runs into his friends, G.H., Gus, and Jack. Having taken a roll of bills from Mary's purse, Bigger implies that his new job has made him wealthy overnight, and he buys his friends packs of cigarettes and hands out dollar bills. In a moment of dramatic irony, they chat about how Mary was in Trader Horn, the movie Jack saw with Bigger early in Book 1:
"Jack was telling me you saw the gal in the movie you suppose to drive around. Did you?"
"Sure."
"How is she?"
"Aw, we like that," Bigger said, crossing his fingers. He was trembling with excitement; sweat was on his forehead. He was excited and something was impelling him to become more excited. It was like a thirst springing from his blood.
This is simple dramatic irony: one of the characters (and the reader) knows information that other characters do not—namely, that Mary is dead. This knowledge makes this scene almost unbearably uncomfortable for both Bigger and the reader. Bigger trembles and breaks out in sweat. Native Son is, at its core, a crime novel, a thriller; Wright here ratchets up the tension with a moment of dramatic irony, as the truth is yet to be revealed.
But Bigger's reaction goes beyond the tension that any liar feels when trying to keep the truth a secret. Bigger's growing desire for action and adventure in his life quickens to a bodily feeling, a need for some kind of action at all moments. This feeling has come out in Bigger before, like when he carried Mary to bed and felt an uncontrollable desire to kiss her: Bigger is often taken up by a passion for action that he cannot suppress. Here, after G.H. mentions Mary, that desire for action becomes a physiological thing: "It was like a thirst springing from his blood." Before this conversation with G.H., Bigger was ready to decide to take action at any moment; after Bigger lies about Mary to G.H., that feeling has become even more innate in his body.