In Slavic, as well as in Nordic mythology, the world is depicted as a sacred tree, usually an oak, whose branches and bark represent the living world of the heavens and mortals, heaven and earth, and its roots the underworld, the world of the dead. It was the tree of life. Perun was the ruler of the world of the living, heaven and earth, and in the roots of the tree lived Veles, who constantly challenged Perun by stealing his cattle, children (son) or wife. Perun chased Veles across the land, attacked him with his lightning bolts from the sky, and Veles escaped by turning into various animals or hiding behind trees, houses or people. Whenever lightning struck, it was believed that Veles hid from Perun in that very spot.
In the end, Perun managed to kill Veles - he drove him into his watery underworld. The supreme god then restored order to the world that had previously been disturbed by his chaotic enemy. Then he returned to the top of the world tree and told Veles that he belongs there and that he should stay there (an ancient Belarusian fairy tale: Ңy, там твое место, там сабе быдь!). In that ritual death, whatever Veles stole would fall from his body in the form of rain from the heavens. That was how the change of seasons was explained. Dry periods were explained by Veles' thefts, and lightning and thunder were considered divine battles. The rain that followed was considered Perun's triumph.
The myth was cyclical and repeated every year - Veles' death was never permanent. He would be reborn again like a snake that tears off its old skin and is reborn in a new body. Although he plays the role of a villain in the myth, the Slavs did not consider him evil. In many Russian fairy tales, Veles took the form of Saint Nicholas, who saved a poor farmer and his cattle from the angry and destructive Ilya the Thunderer, who represents the god Perun. Their struggle does not represent a dualistic struggle of good and evil, it was probably the opposition of the natural elements of water and earth - Veles and sky and fire - Perun.