Birth and Death
Manion was born on thinking machine-occupied Earth to Serena Butler after she had been captured by the forces of Omnius and taken as a slave by Erasmus. Manion was the illegitimate child of Serena and Xavier Harkonnen. He was named after his esteemed maternal grandfather Manion.
Though Manion's delivery was greeted with curiousity and excitement by Erasmus, he was quickly deemed by the robot to be a distraction to his mother. In an attempt to regain Serena's full attention Erasmus killled the infant Manion by throwing him from the top of a tower on his estate. But the action evoked the opposite reaction, and in a fit of rage and despair Serena destroyed a thinking machine guard and triggered a slave uprising that ultimately resulted in the beginning of the Butlerian Jihad.
Manion's body was spirited away on the Dream Voyager and taken to Salusa Secundus along with his mother, Vorian Atreides and Iblis Ginjo. There he became deified as a martyr and the fulcrum of a ferocious and protracted war against the thinking machines.
Behind the Scenes
Manion was never explicitely mentioned in Frank Herbert's original novels. The character does, however, play an important role in the Legends of Dune trilogy written by Brian Herbert and Kevin J. Anderson.