This overlay enforces a sharp tonal shift. The story begins lighthearted — casual, playful, even humorous (a simple deal, a joke wager, a harmless test). Slowly, hints of unease creep in until the tone flips. By the midpoint, the mood should become oppressive and grim, as the stakes turn dire and the character realizes the bargain is a nightmare. The pacing should emphasize contrast: laughter in the first half, silence and dread in the second.