In Diablo IV, Inarius plays a significant role as one of the key characters in the game's lore. Inarius is an archangel who, alongside the demoness Lilith, created the world of Sanctuary as a place of peace away from the Eternal Conflict between Heaven and Hell. Their union led to the birth of the Nephalem, the ancestors of humanity.
However, Inarius and Lilith's relationship became strained due to their differing views on how to handle the Nephalem's potential power. Inarius wanted to control their influence, while Lilith wanted to harness it. This disagreement led to Lilith's banishment and Inarius becoming a self-proclaimed ruler, establishing the Cathedral of Light to enforce his ideals.