Arvis serves as one of the main antagonists of the game. He is convinced to marry Deirdre, both unaware that they share the same mother and are thus half-siblings. The result of their union are twin children, Julia and Julius. Arvis kills Sigurd and his companions in the Battle of Belhalla, slaughtering almost all of the first generation. Later, he ascends the throne as Emperor of Grannvale and rules a generally stable nation for several years. However, once Manfroy presents Julius with the Book of Loptous, the wicked god seizes the boy's body, slays Deirdre and wrests all power from Arvis, rendering the latter a glorified prisoner who can only watch as Loptous twists his life's work into a new Loptrian Empire. Arvis ultimately meets his end by the blade of Sigurd's son, Seliph.
When fought as an Einherjar in Awakening, Arvis may interact with Chrom, which reveals that historical documents on Jugdral millennia later have come to vilify Arvis for the land's descent into Loptrian terror, not Loptous.
