Darius is an antagonist and Seventh Son.
Darius was the seventh son of a priest and just as Henry bonded to a dandelion, he was bonded to a mushroom. His actual christened name was Fred. He kidnapped Henry and tried to make him his son. He was then taken over by Nimiane the witch queen and controlled by her. He was killed by the Arrow of Ramoth Gilead, or Arrow of Chance, by Caleb on a bridge in Hylfing during Nimiane's attempt to destroy the city.
Darius is described as enormous, with a large hooked nose, protruding jaw, and thick, curling sideburns. He was at least half a head taller than Frank Willis. Henry thinks he looks like a Pilgrim with his tall hat and silver buckle. But he was actually projecting an appearance just like Nimiane did. He was actually scrawny and had large ears and a tiny jaw that he’d attached an ivory prosthesis to.