Guardians are an Incarnation of Angels created by the God-Machine that act as protectors of the interests of it's Creator. Guardian Angels often find themselves on missions that are either extremely short, in order to neutralize a threat to a Keystone, or can extend over decades, like protecting a pregnant woman and her child until the child turns twenty. Some were assigned to particular Angels in order to ensure their success.
As Unchained, Guardians seek things worthy of their devotion. This devotion, however, can appear to humans as extremely clingy, with stalker-like obsession.
Most Guardian Angels Fell because they became too entangled in the world and the fate of their target. Some were called back to be recycled, but refused in order to continue their watch. Others were faced with the failure of their mission and could not cope, others came to believe that the God-Machine was the greatest threat to the target and Fell out of devotion. Some couldn't stand the pressure of averting the numerous threats to their target and snapped, Falling in the process.
The Guardian tendency for caution to the point of paranoia and watchfulness to the point of obsession is also hard-wired into their psyche, and Shields must find ways to manage these urges as they move through their Descent. Antinomian Guardians refuse to intervene when disaster strikes those around them, training themselves to be mortal by ignoring their finely-tuned sense for impending doom. Most Shields, though, find a level of caution they are prepared to accept, relying on Embeds to react with lightning speed to imminent danger without spending every waking hour over-preparing.
Some Guardians find having close companions triggers too many of their instincts and opens them to danger - and the danger a Guardian senses is never imaginary, even if it's highly unlikely. These demons apply their protective instinct and their uncanny situational awareness in more removed ways, taking jobs as first-responders, selling their loyalties and skills while maintaining professional distance, or choosing a cause to champion by "protecting" a concept rather than an object or person. Shields typically maintain few close friends; preferably ones who will tolerate their instinctive need to be the protector. They are serial monogamists and truly devoted friends.
- , p.102-103