Ruby Hudole is an agent with the Order.
One blurb for the first recorded adventure made mention of her working for the Institute but I found no reference to such an organization so I moved on. There are many mentions, though, of the Order of the Watchers, "the secretive group [Hudole's] parents had once served, dedicated to preventing the apocalypse. Hadn't really worked out the way they'd planned, apparently". When I describe the state of the world that Hudole lives in, you will see the reason for that last sentence.
Whether Hudole actually is employed by the Order or simply works with them on a shared goal is a bit debatable and not really worth the time since she does what she does for her own reasons.
Now is the time to mention that Hudole is a Fae. As a member of that race of beings living on Earth next to and amongst humans while working diligently to not be discovered as such an exotic creature. As all Fae, she has some interesting powers. One of hers is the ability to transform into other humanoid form so as to pass by or join in. One she is especially good at impersonating is a succubus; she does wonder if there career in New York as a burlesque dancer prior to Great Nightmare might have something to do with that.
Which brings us to that apocalypse mentioned earlier, an event that everyone who lives on Earth calls the Great Nightmare. That is the time that the demons came forth, which was bad, and then the Angels came down, which was far worse. Tens of thousands would soon die and many more as time went by. Humans and Fae both suffered horribly under the new regime and the Order found renewed purpose in that fight.
Hudole would be forced to become an operative to first find her missing sister and then to continue on the fight against the oppressors. This red-haired, green-eyed beauty would become, as the tagline states, a 'spy among the Fallen', becoming close to the Angels to strike better at the Gods that now ruled the world.