Shade

"It has often been suggested that the only way for a demon to affect the world of the living is by possessing a living (or once living) body, but this is not always true. Indeed, a shade is one such creature: a demon in its true form that has adapted to affect the world around it.

My hypothesis is this: We already know that many demons become confused when they pass through the Veil into our world. They are unable to tell the living from the dead, the very static nature of our universe being confusing to a creature that is accustomed to a physicality defined entirely by emotion and memory. Most demons seek to immediately seize upon anything they perceive as life, jealously attempting to possess it--but what of those that do not? What of those that encounter no life, or fail to possess a body? What of those that are more cautious by their nature?

These demons watch. They lurk. They envy.

In time, such a demon will learn to drain energy from the psyche of those it encounters, just as it did in the Fade. Once it has drained enough, it has the power to manifest and will forever after be known as a shade. Such a creature spurns possession. It instead floats as a shadow across its piece of land, preying upon the psyche of any who cross its path. Perhaps it believes itself still in the Fade? There is evidence to believe that is so.

A shade will weaken the living by its very proximity. If it focuses its will, it can drain a single target very quickly. Some have even been known to assault the minds of a living victim, causing confusion or horror and making the target ripe for the kill. The tragedy of a shade is perhaps that, once it has drained a target whole, its appetite is only heightened rather than slaked."

--From the journal of former Senior Enchanter Maleus, once of the Circle of Rivain, declared apostate in 9:20 Dragon Age.