In Greek mythology, chthonic deities, such as Hades and Demeter, influence the living by controlling aspects of life, fertility, and the afterlife. Their presence underscores themes of death, rebirth, and the cyclical nature of existence. These deities remind the living of their connection to the earth and the inevitability of mortality. Their stories often reflect the consequences of human actions on the natural world, emphasizing the importance of respect for both life and death.