Apostrophe
Apostrophe — direct rhetorical address to a personified hearer who is not actually a person — collects two passages, both of them speeches turned upon Death and the grave. The earlier text is in Hosea; the later, in Paul, picks up the same figure to celebrate its undoing.
Hosea: Death Confronted
In the middle of a redemption oracle, Hosea turns from speaking about Death and Sheol to speaking to them: "I will ransom them from the power of Sheol; I will redeem them from death: O Death, [my Speech] will be your plague. O Sheol, I will be your destruction. Repentance will be hid from my eyes" (Hos 13:14). The pivot from third-person promise ("I will ransom... I will redeem") to vocative confrontation ("O Death... O Sheol") is the figure: Death and the grave are addressed as if they could hear and answer.
Paul: Death Mocked
Paul takes up the same figure at the climax of his resurrection chapter, addressing Death directly with two parallel taunts: "O death, where is your victory? O death, where is your sting?" (1Co 15:55). The personified hearer is the same — Death itself — and the rhetorical posture is the same: a direct vocative addressed to a power that, in Paul's argument, has been dismantled.