Snakes are a mixed bag in terms of symbolism. In a lot of cultures, they’ve been view positively, symbolizing life, immortality, or resurrection, and also associated with wisdom or hidden knowledge.
It would be easy to blame their negative reputation entirely on the Garden of Eden story; after all, the middle eastern cultures even older than that are among the ones where serpents were associated with knowledge, as the one in Eden itself still is, just flipped around to be considered a bad thing. This is only one of several examples in Judeo-Christian tradition of literal demonization of figures from other religions.
But I don’t think that’s entirely it. Snake monsters exist in several other mythologies, independently; including some of the same ones where snakes kept their positive associations as well, such as the Greeks, where the snake was on the rod of the god of healing (still a widely used medical symbol even today), but also seen in such forms as the hydra and Medusa’s hair. And it’s at least speculated, if not proven, that snakes are a primal fear of humanity, a fear older than any positive or negative religious view of them
Still, I like the positive symbolism, both traditional and the kind that comes from alternate perspectives of the Eden story. So in Project Quintessence, Ertiada, whose arrival brings knowledge and wisdom, has as her VG the Serpens.