Mohiam is instructed by the Bene Gesserit to collect the genetic material of Baron Vladimir Harkonnen (through conception) for their breeding program. She blackmails the homosexual Baron into fathering a child with her. When that daughter proves genetically undesirable, Mohiam kills it and then returns to Harkonnen for a second try, at which point he drugs and viciously rapes her. She exacts her retribution by infecting him with a disease that later causes his obesity. Mohiam kills her first child with Harkonnen, and their second child is Jessica, Harkonnen's paternity having been previously established in "Dune".