The Collector is a trophy hunter from another plane of existence, manifesting in ours as a ghostly old man. Having caught them all (so to speak) in his home dimension, he learned to project himself across dimensional boundaries in search of still more exotic specimens. It is possible that one or more of these other dimensions serve as stage and props department for dreams and prophetic visions.

In addition to his own form, he has also learned to project other creatures freely across planes of existence. Depending on his will, they can be (or not be) as material and substantial as if they really existed on that plane.

In general, he prefers his specimens alive so that they can be repurposed as hunting dogs (or demons). Unwilling specimens are incarcerated in the usual way. In the case of specimens killed in the hunt, his dimension-crossing abilities allow him to harvest something of their soul, so that a darkly luminous shape of them persists in our world as a trophy, a sort of supernatural scalp.

His hunt in this plane is headquarted at the castle where Captain Josia leads her crew in Book 3. Intruders are captured and made part of his collection, after being killed and re-animated if necessary. He alters deals and encourages others to pray he does not alter them further.