According to the myth, Nidhogg was a dragon that lives under the roots of Yggdrasil the Great Tree connecting the Nine Worlds . Deep down there, Nidhogg ate corpses. As Yggdrasil was rooted in Helheim – the place of the Dead, Nidhogg was sometimes considered to be the symbol of death. In many depictions, Nidhogg was a giant dragon with evilly shining eyes in the darkness. His body encompassed the roots of Yggdrasil with its deadly jaws open and intending to eat corpses and roots.
Through a squirrel Ratatosk as a communicative means, Nidhogg and an eagle flying on the top of Yggdrasil sent insults and ridicule to each other. However, Nidhogg stayed harmless until the days of Ragnarok finally arrived. And the historical and mortal days were looming large. Nidhogg joined the evil side, carrying the corpses within it wings to partake the final combat with Gods and human.
After all, Nidhogg was of few figures that survived Ragnarok and it carried the ever-present threat to the new beginning of the cosmos.