A Tracker is an adult vampyre who is chosen to Mark young humans into fledglings. When a human is meant to be Marked, a Tracker becomes aware. First, their spiral labyrinth tattoo on their right palm will begin to burn and look raised, like a brand. Then they will be hit with a uncontrollable compulsion to get to the place, time, and name that gets put into their minds. It is almost impossible to ignore this urge. A Tracker remains in Nyx's service for four years. A Tracker can travel, but only if their blood calls them to Mark a kid that belongs at a certain House of Night. A Tracker can scent Alarm Pheromones. When the human is in the Tracker's presence, the Preservation Pheromone only a Tracker secretes begins to act on the person's T-cell receptors to slow down the degeneration of their pulmonary capillary system. The human is tracked down, and the Tracker raises their finger to the human's forehead and says the incantation:
|“||[Person's name]! Night has chosen thee; thy death will be thy birth. Night calls to thee, hearken to her sweet voice. Your destiny awaits you at the House of Night.||”|
— A Tracker when a human is being Marked
They are then Marked with an unfilled crescent moon tattoo in the middle of their foreheads, which can be either blue or red in color as of Destined. If the Tracker says the incantation wrong, the fledgling will be Marked as a Red Fledgling.