Through most of Fourth Wing, venin are treated as a legend. They are creatures most people believe are myth, the kind of story told to scare cadets. By the end of the first book, that belief collapses: venin are revealed to be very real and a serious threat.
The reveal is a turning point for the series. It tells the reader that the world's official history is not the whole truth, and that the dangers everyone dismissed as folklore are already moving at the edges of the story.
This page keeps details light to avoid major spoilers for the later books. The exact nature and goals of the venin unfold across the Empyrean series.