Felix is the only child and heir of magister Gereon Alexius and his wife Lady Livia Arida. Though he showed signs of magical ability, his talent proved so limited his grandfather tried to have him assassinated for being "just barely more than a Soporati". His mother countered the attempt, and then had her father in-law killed to safeguard her son's future.
Since Felix couldn't learn much in the way of spells, his father brought in tutors to teach him history, art, music, literature and anything else he could want to study. Felix eventually showed a talent for mathematics, and was sent to the University of Orlais to study with the best.
When his father took Dorian Pavus on as an apprentice, Felix would secretly sneak him treats when Dorian was up late studying.In 9:38, while Felix was making the trip back to Hossberg from the university for the winter holidays with his parents, their party was attacked by hurlocks. Though the creatures were driven off, Livia was killed in the attack and Felix caught the Blight sickness, condemning him to a slow death.
Felix accompanied his father to Redcliffe, where Alexius had forced out Arl Teagan and manipulated the rebel mages into servitude. While Alexius was in the midst of negotiations with the Inquisitor, Felix feigned illness so he could pass a note to the Inquisitor, instructing them to go to the village chantry. Afterwards, Felix ditched his father and attended the meeting with Dorian. He reveals that his father is part of a Tevinter supremacist cult called the Venatori and are very interested in the mark on the Inquisitor's hand.
Should the Inquisitor choose to confront Alexius, Felix openly turns against his father and attempts to convince him to give up on his plans, but Alexius states that the Elder One can save him. As Inquisition agents kill Alexius' retainers, Alexius activates his time amulet in an attempt to change the past, Dorian interrupts him, accidentally sending both himself and the Inquisitor one year into the future.
In this bizarre future, where the Elder One dominates southern Thedas, Felix's condition had worsened. When Leliana takes him captive and Alexius identifies him, Dorian is mortified at what his former mentor had done to his son. Regardless of how the Inquisitor responds, Leliana slits his throat.
After defeating Alexius, the Inquisitor and Dorian return to the exact moment they left, and force the magister to surrender. Alexius bemoans his inability to save his son, but Felix states that he accepts his impending death.
Felix soon returned to Tevinter and informed the Magisterium of what occurred at Redcliffe, but died soon after.If the Inquisitor sided with the Templars, Dorian attempts to discover what happened to Felix with no success. Dorian believes that Felix was killed by the Venatori for aiding him.
- Dorian says that Alexius wasn't with his wife and son when they were attacked and blames himself for not being there to save them.