Nidhogg Fafner is one of the seven God Warriors serving Andreas Lise, the new representative of Odin in Asgard. He wears the God Robe of Nidhogg, a dark armor with black, deep purple, and navy tones, and wields the sword Ridill, which can shift between a whip and a lance form. Fafner is known as the most cruel and malevolent of the God Warriors. He is a ruthless and sadistic individual who shows no regard for human life, conducting horrific experiments on captured villagers to advance his work. He is also highly arrogant and confident in his own abilities, regarding himself as an evil genius. His primary motivation is to serve Andreas by developing Yggdrasil, the sacred tree, increasing its ability to absorb cosmos, and creating new Odin Sapphires through his experiments. He takes a direct role in the story as the guardian of Svartalfheim, one of the inner chambers of Yggdrasil, and is the first adversary of Mu of Aries after the Gold Saints mysteriously revive in Asgard. Fafner captures innocent people to fuel his research, and when Mu confronts him, Fafner attempts to trap him using the roots of Yggdrasil to drain his cosmos. He later appears alongside the other God Warriors when Andreas gathers them, and he is saved by Andreas when he finds himself in trouble during a fight against the Gold Saints. Fafner has little personal development; he remains a committed antagonist throughout his appearances. His notable abilities include Dragonewt Bullet, which fires spirit spheres of concentrated cosmos from his sword; the Ridill itself, which he wields with versatile forms for offense and defense; and the manipulation of Yggdrasil's roots to ensnare enemies and absorb their energy, a technique he uses to empower himself and his Odin Sapphire.