On earth, Arkarian works in a set of chambers within a mountain (identified by his Apprentice Ethan as being located on "the south-western slopes of the Great Dividing Range), the entrance to which he can access mentally. Some of the rooms "change often, though it is unclear whether they do so of their own accord or by external influence. The main, octagonal chamber is used for briefings and meetings, and it is fitted with special equipment that allows Arkarian to monitor other time periods, and with them, the Guard's missions - particularly those involving Ethan and Ethan's later Apprentices.
While in the first book, Arkarian is seen supervising the Guard's missions rather than undertaking them directly, The Dark finds him sent to Medieval France with Isabel, where they are attacked by Lathenia herself. Arkarian manages to fend her off, but she promises they will meet again, turning threat into reality when she has him kidnapped and brought to her in the underworld.
Because of that particular world's danger, Lorian forbids the Guard to launch a rescue attempt. Isabel, whose feelings for Arkarian have grown substantially, ignores the edict and enters the underworld with the help of the Guard's royals. Ethan and her brother Matt go with her, the first out of his loyalty for Arkarian, and the second for Isabel's protection. When the three find Arkarian, he is severely injured, and uses his remaining strength to warn them of Marduke's resurrection. Isabel heals him, but not before Lathenia comes back. Her magician, Keziah, attempts (and fails) to bind Arkarian's powers, which enable him to open the rift between the worlds and thus escape.
After hearing that his rescue violated a direct order from Lorian, Arkarian pleads with him for Isabel's absolution, and asks for his gift of agelessness to be taken away in oder to be with her. Lorian exonerates Isabel publicly, telling the Tribunal that his prohibition was a test designed to find the bravest candidate to face the horrors of the underworld, not a testament to Arkarian's expandability. Before ending the trial, Lorian honors Arkarian's request not by stripping him of youth retention, but by giving Isabel the same gift.
In The Key, Arkarian is pushed into the background as the story is told by Matt and Rochelle. His relationship with the former is problematic, as Matt is overprotective of Isabel and distrustful of Arkarian's feelings for her.
After spending the first eighteen years of his life as a foundling with no status, Arkarian became indentured into the Guard. For two hundred years following, he was Lorian's Apprentice, whereby he acquired skills necessary to fight immortals.
From Ethan's comparison of Arkarian to the Tribunal members, and the beauty of both his parents, it is assumed that Arkarian is good looking.
Though it is never expressly stated which of his powers are innate, and which are gifts, it is assumed that Arkarian's natural skills are telepathy (dubbed TruthSeeing in the universe of the Guardians of Time) and a form of telekinesis. The latter, never actually named or explained, manifests itself in an ability to make objects appear and disappear at will. In addition, Arkarian is able to give comfort through touch. The true quantity and extent of his powers, those given by the Tribunal and learned from Lorian or otherwise, are unknown. Also he is able to make pain subside through touch.
Not long after, Isabel realizes that she is attracted to Arkarian, but the two appear unaware of one another's feelings. At one instance, Arkarian confesses to Isabel that he would die for her, but their relationship still fails to progress. It is only when Isabel breaks into the underworld to save him that he realizes that his love is reciprocated.