Starting in her early 20s, Vigil joins a monster-hunting organization called the Conclave of Blood, whose goals are primarily finding monsters that would hide among people in cities and towns, including things like werewolves, vampires, and cults and cultists of all types. Her initiation ritual gave her an infusion of dragon's blood and the ability to use a bit of magic to aid in seeking and hunting things, also resulting in the golden scales and slit pupils present here.
Most pictures I have of her are from a few years prior to that, and so lack the scales.

Art by DragonFU