Why is the wolf both a threat & a savior in Russian fairy tales?

The nature of the fairy tale wolf is complex. On the one hand, it’s a forest dweller, which the ancient Slavs associated with the "other world", the world of the dead. It’s a source of danger. On the other hand, it’s a mediator between worlds, as it can freely enter the human world and even assist the fairy tale hero in his difficult trials, as shown in the tale ‘Ivan Tsarevich and the Gray Wolf’.

According to the classic theory of folklorist Vladimir Propp, a fairy tale is constructed from a set of recurring functions that can be performed by different characters. The Gray Wolf in this framework is a typical "miraculous helper", a creature that provides the hero with a magical remedy, transports him, obtains necessary items and, ultimately, saves him from death. The wolf replaces the hero's horse, carries him over vast distances and shows him the way to the Firebird, the golden-maned horse and Elena the Beautiful. After Ivan is killed by his brothers, the wolf revives him with the help of dead and living water. The wolf speaks with a human voice, warns the hero of dangers and gives him instructions.

Thus, the wolf combines several roles within itself, which, in other fairy tales, might be distributed among different characters. At the same time, it retains the duality of its nature: before helping Ivan, the wolf eats his horse, which can be interpreted as a sacrifice to the underworld.