Vishnu’s role as the maintainer of the world involves this function of mediator, or moderator, between the antagonistic energies that are active in the life-process of the universe. He restrains the overbearing impact of the destructive, disruptive powers.
Zimmer defines Vishnu’s essential psychological function as mediator between destructive and productive cosmic energies, descending through avatāras to restore equilibrium without ever eliminating the demonic polarity.
, Myths and Symbols in Indian Art and Civilization, 1946thesis