Dex is a rule follower.
Dex is handsome and has dark skin with pale eyes. He wears the usual black armor of a Mask. When he is promoted to steward, he also wears a blue and gold cloak.
Dex is a fellow student at Blackcliff Academy with Elias and Helene. Dex is the one who brings in the deserter, Falconius Barrius. After the young boy dies from his punishment, he escapes to a brothel with Faris Candelan. Dex participates in the Third Trial. He unwillingly kills Tristas before he can kill Elias. Dex is the one who begs Elias to order his platoon to kill instead of injure so that they can win the Trial. Dex is revolted and sickened with what he and his classmates were ordered to do by the Augurs for the Third Trial.
Helene promotes Dex to her Black Guard. He helps her track down Elias. Helene promoted him because she needed someone she trusts near her.
Dex travels to Navium with Helene and Avitas. His uncle, Janus Atrius is there with the other leaders of Navium. He is the Pater of Gens Atria. Helene sees Dex flirting with Lieutenant Silvius after the attack on Navium.
Dex returns to Antium from Navium. He tells Helene that Keris knows she has been spreading the truth about her tattoo and the murders of the Illustrian Masks. She sent two assassins but Dex killed them. He reports that Keris stopped at Raider's Roost and he was unable to discover what she was doing there. Helene sends Dex back out on the road to check the passes around the Nevennes for Karkauns. Helene wants to make sure they aren't pushing for Delphinium.
Dex has become Empress Regent Livia's steward.
Dex ends up becoming the Commander of Blackcliff Academy. He is living in Serra with Lieutenant Silvius. Dex is running the school in a very different way. Silvius used the whipping post as kindling. They will welcome the first class of female recruits in a month. Dex and Silvius have been rebuilding the school after it was destroyed in the bombing to free Elias.
- The name Dex means "right-handed" in Latin.