During the quest "Breaching Security," he is assigned by his father to verify the security of each major hold in Skyrim. If the Dragonborn joins the Dark Brotherhood, Gabriella sends the Dragonborn to eliminate him, hoping to weaken his father's leadership and distract him from his duties to the guard, thus leaving the Emperor vulnerable to an assassination attempt. The Dragonborn is to murder him in one of the cities and plant an Incriminating Letter on his corpse. The letter describes a thwarted assassination attempt, meant to further leave the Emperor unsuspecting of an assassination attempt.
Gaius Maro follows a specific schedule, departing from Dragon Bridge and traveling to each major hold in Skyrim. He was also assigned to monitor Windhelm's security and even sleep in the barracks despite the ongoing hostilities between the Stormcloaks and the Imperial Legion.
- It can be assumed that he is in some sort of romantic relationship with Faida, the innkeeper of Four Shields Tavern, as they share an intimate farewell when Gaius leaves on his mission.
- Gaius is voiced by Gideon Emery.