Spoiler alert: This information is extremely new and can spoil the story for readers who haven't read the story till its last update. Proceed at your own risk.
The Couriers are an unknown race of information dealers. It is not known where they come from or what they are exactly even though it is said they were around for thousands of years.
Their bodies are hidden by dark gray cloaks except for their hands or head which instead is wrapped around sandy brown bandages-including the eyes,nose and mouth.
It seems that every Courier has the power to teleport. They can be called by a special mirror, which looks especially foggy.
Each Courier has its own mirror and gives the mirrors to servants with considerable wealth and influence.
The Courier only responds to the servant with the mirror and no one else. Though it is yet unknown how they choose servants to give the mirror to.
Due to their abilities of information dealing, they are neutral to the conflict of Abolish and Vanguard. They are also known to be able to keep sensitive information secret.