|Black Ship pirates
Referred to as "Dark Majesty" and "your Holiness", the Ebony Cardinal was a leader of the fleet of the Black Ships. Apparently the Ebony Cardinal, a rather corpulent and decadent figure, was seen as the Nameless One incarnate. The Nameless One was apparently a deity or figure of great regard in the Black Ship culture. Such exclamations as "Praise the Nameless One that provideth this bountiful feast" help to demonstrate this.
To the surprise of Atrus' sons, the Black Ship culture had developed advanced technology like the forging of steel, steam-driven harpoons, and the like.
Sirrus and Achenar swore an oath to the Ebony Cardinal to be his sons, to "embrace the wonderment of death", and to accept the Black Ship way of life.
The end of the MYST comic book indicates that Achenar, at least, continued to see the Ebony Cardinal as his father, and delivered a D'ni Book into his hands.