In appearance, Arcanus appears to look identical to Alex the antagonist of Golden Sun and Golden Sun: The Lost Age. However, he doesn't appear to look 30 years older as the other members of the Golden Sun Event do, including Isaac. On his site Biography it states that the Warriors of Vale know what his face looks like and would be able to recognise his true identity, not hiding it from those that knew him thirty years prior to the story of Golden Sun: Dark Dawn. Despite his "true identity and nature being shrouded in mystery" his impact on Matthew's adventure will impact heavily on the success of the children of the Warriors of Vale's mission.
Before the activation of the Apollo Lens, he reveals himself to be Alex. This revelation angers Rief due to the betrayal of his mother, Mia, in the Golden Sun game after letting Saturos and Menardi into the Mercury Lighthouse.
At the end of Golden Sun: Dark Dawn he appears atop of the Apollo Lens and distracts Blados and Chalis so that Matthew, Tyrell, Karis and others can activate the Apollo Lens to deactivate the Luna Tower. After his fight, he is never seen again, although it is said that Matthew could hear his voice when atop of the Sol Lens, calling him to stop. The reason for his demands and his true motives were never revealed.