Jörmungandr, the World Serpent, plays a key role in both 2018's "God of War" and "Ragnarok," but gamers get to see Atreus “birth” Jörmungandr by infusing a younger version of him with the soul of a giant. This young Jörmungandr is summoned to Ragnarok, beaten back by Thor, and presumably sent back in time to the previous game, but his exact journey is still unknown.