Duke Perrington is the cousin of the King of Adarlan, and rules the Duchy of Morath. In Throne of Glass, he sponsors Cain. It is revealed that he is inhabited by the demon king Erawan, and it planning to use the wyrd keys to release more Varg into Erilea.
Duke Perrington is said to be a large man. He has obsidian eyes and red thinning hair. He also has a sandy mustache and meaty hands.
Perrington is cruel, manipulative, and scheming. He is also prideful and has shown perverted tendencies.
Perrington travels with Prince Dorian Havilliard and Chaol Westfall to Endovier to retrieve Celaena Sardothien. When Celaena does not bow before Dorian, Perrington tackles her to the floor and berates her. Dorian reprimands Perrington, remarking that he knows Perrington respects him but that his attack on Celaena is only meant to humiliate her.
Perrington is revealed to be the significant other of Kaltain Rompier, who snagged his attention in the hope that he would bring her to Rifthold.
It is later confessed by the King of Adarlan that the Duke was inhabited by the demon king Erawan.