Nothing is known about Mastermind’s life before the time when, while working as a carnival mentalist, he was enlisted by Magneto as a member in his Brotherhood Of Evil Mutants. More recently, Sebastian Shaw and Emma Frost, the mutants who lead the Inner Circle of the Hellfire Club, invited Mastermind to test for admission to the Inner Circle as part of their ongoing program of recruiting super-powered mutants for their organization. To prove his worth, Mastermind, using both his natural powers and artificial means, psionically altered the personality of Jean Grey, so that she willingly became the Inner Circle’s new Black Queen. However, in doing so, Mastermind unintentionally triggered Grey’s transformation into the insane Dark Phoenix.
Grey broke free of Mastermind’s control, and opened his mind to all the various psionic sense impression that she herself received from the cosmos as Dark Phoenix, impressions which no ordinary person or even any ordinary psionic ever receives. The strain of dealing with such psychic awareness was a contributing factor to Grey’s insanity as Dark Phoenix; Mastermind, on being given such awareness all at once without any training in how to cope with it, immediately fell into a catatonic state. He is now a patient at the Jung Mental Institute, a Massachusetts institution for the mentally ill. The Inner Circle has rejected his application for membership. How long Mastermind will stay in a catatonic state, however, remains to be seen. Although Jason Wyngarde is gone, his name and powers live on through his daughters: Regan Wyngarde, calling herself Lady Mastermind and Martinique Jason, taking her father's codename.