Fafnir (Marvel Comics) entities is stopped when Thor agrees to go to Hel's realm willingly. Fafnir later reappears in the 2011 limited series "Avengers Prime" in the aftermath of the "Siege" storyline as, at first, an adversary then ally of Thor, Tony Stark and Steve Rogers with several legions of ogres and elves in battle against a Twilight Sword wielding Hela and her army. Fafnir was originally a normal man until transformed by the properties of a magical pool into a large dragon. Fafnir retains his intellect and speech, possesses superhuman strength and durability, and the ability to breathe fire and cast illusions.
Sacred trees and groves in Germanic paganism and mythology groves are widely attested among the records of the ancient Germanic peoples. Some scholars hypothesize that they even predated the development of temples (according to Rudolf Simek, "there were sacred woods long before there were temples and altars"). In his "Germania", Tacitus says that the Germanic peoples "consecrate woods and groves and they apply the name of gods to that mysterious presence which they see only with the eye of devotion", Tacitus describes the grove of the Semnones and refers to a "castum nemus" (chaste grove) in which the image of the goddess Nerthus was hallowed, and other reports from