Raised in Vale, in the land of Weyard, he is the brother of Jenna. On the day of the tragedy of Vale, when Mt. Aleph erupted and the boulder came crashing down upon Vale, Isaac lost his father and Jenna lost her parents and her brother Felix in the incident. It was not until three years later that Isaac, his friend Garet, and Jenna traveled with the scholar, Kraden, to the forbidden Sol Sanctum in order to get the orbs to awaken an age of prosperity across the land. It was there that two Adepts, people who wield Psynergy, came to take the crystals. Their names were Saturos and Menardi, from the Mars Clan, the Adepts from the far north who use Fire. Along with them, they had a masked man, who turned out to be none other than Felix himself. Saturos and Menardi held Jenna and Kraden hostage for the last elemental orbs, and Felix cooperated with the mysterious villains in order to use the orbs to light the Lighthouses across Weyard to awaken the Lost Age. Isaac was determined to stop them from their treachery.

Later on, Isaac had defeated the two at the Venus Lighthouse, and the lighthouse erupted, forcing Isaac and Felix to separate once again. Both continued their separate quest; Isaac to stop the lighthouse lighting, and Felix to finish Saturos' job. The Lost Age puts the player in control of Felix, who aims to fulfill his duty to awaken the lighthouses. Eventually comes a decision when he meets Isaac again. Must he battle his friend to obtain his goal, or would a much deeper tale convince Isaac of the truth otherwise...?