Reverend Mother Gaius Helen Mohiam was a Bene Gesserit Reverend Mother, who was secretly the mother of Jessica Atreides, and the grandmother of Paul Atreides. Mohiam was completely loyal to the Sisterhood throughout her entire life, never wavering in her commitment through the end of the Corrino Empire, to the Ascension of House Atreides.
As a Breeding Mother
Mohiam was born as Tanidia Nerus. The Bene Gesserit had matched her with male trainers throughout her childbearing years, and she had delivered eight daughters to the Bene Gesserit school, all of them raised apart from her on Wallach IX, or on other training planets.
In order to become a Reverend Mother, she had been required to alter her own biochemistry by taking an awareness-spectrum poison. In transmuting the deadly drug within herself, she had passed inward through the long echoing bloodlines, enabling conversation with all of her female ancestors, the clamorous inner lives of Other Memory.
She played an important role in the breeding programs of the Sisterhood on Wallach IX. Armed with the financial records of House Harkonnen, stolen earlier by Margot Reshino-Zea, she visited Baron Vladimir Harkonnen in Harko City.
She explained to the reluctant Baron that she was supposed to be impregnated by him for their breeding programs and conceive a daughter. The Baron, loathing women and having other sexual preferences, was also hostile to her and the Sisterhood. As a response she threatened him with a full-scale Guild bank audit of his activities and revocation of his temporary CHOAM directorship.
Later, however, the girl born in Birthing Room One, being the ninth child she had borne, was the hardest of her births. The baby was born sick with misshapen bones. The disparity between its bioresult status and the optimal numbers were striking; the baby was a mistake, and Mohiam killed the child herself.
When she returned to the Harkonnen Keep, she was told by Burseg Kryubi that she should enter alone, without guards. The Baron, who already gave his consent to representative Margot Reshino-Zea, had prepared his revenge on her. As she met him, Piter De Vries shot her with a neural scrambler and she was paralyzed. Even with extreme prana-bindu muscular control, she couldn't move.
Mohiam conceived her daughter through a vicious rape by the Baron, who attacked Mohiam out of pure rage and disgust, in order to show the Sisterhood that he could not be used as a pawn in their schemes. But his satisfaction in overpowering was short-lived, for Mohiam, using her Bene Gesserit training, transferred a latent degenerative disease she had stored in her body chemistry, into the Baron, via intercourse. This disease would mutate his beautiful male form into a bloated, obese monstrosity.
The child born was named Jessica, and Jessica's parentage was kept secret from her. The breeding charts listed her mother with Mohiam's own birth name, Tanidia Nerus.
Training the Atreides
Mohiam trained the Lady Jessica in the Bene Gesserit chapterhouse on Wallach IX. Two decades later, Mohiam tested the young Paul Atreides before his departure for Arrakis with the gom jabbar. The test was to discover whether Paul was "truly human" by trial of pain. The pain inflicted on Paul was caused by nerve induction and clearly drained an incredible amount of energy from the Reverend Mother, since no male child had ever withstood that much physical pain before.Mohiam joined the conspiracy to topple the rule of Paul Atreides after he ascended the Golden Lion Throne and unleashed his Jihad upon the Empire. She, along with Scytale (a Tleilaxu Face Dancer), Edric (a Guild Navigator), and Princess Irulan (embittered wife of Paul Atreides), plotted to insinuate the Tleilaxu ghola Hayt into the court to weaken Paul's confidence in his prescience and thereby ruin him. When the plot failed, she was executed in the retaliation initiated by Regent Alia after Paul walked into the desert after the death of his wife Chani.