Gaius Helen Mohiam - Dune

Dune

As Dune begins, the "old crone" Reverend Mother Mohiam comes to Caladan to "test" young Paul Atreides before his departure for Arrakis. Having trained Paul's mother Lady Jessica at the Bene Gesserit school on Wallach IX decades before, Mohiam now holds a lethal gom jabbar to Paul's neck. If he withdraws his hand from a box that inflicts pain through direct nerve induction, the gom jabbar will kill him instantly. Mohiam explains to Paul that the purpose of the test is to discover whether Paul is "truly human", by requiring him to endure pain and still act rationally. He passes the test, and Mohiam (though still furious over Jessica's choice to disobey the Sisterhood and bear a son instead of a daughter) is somewhat intrigued by the potential she sees in 15-year-old Paul, as she notes he has survived more pain than any other Bene Gesserit inductee.

Later, Mohiam accompanies Emperor Shaddam Corrino IV to Arrakis in her role as Imperial Truthsayer; there she is faced with Paul's four-year-old sister, the pre-born Alia, whom she calls an abomination. Mohiam is further alarmed as she witnesses the ritual battle-to-the-death between Paul and Feyd-Rautha. Paul calls Feyd "cousin," revealing that Paul is aware of the secret that the Baron Harkonnen is his grandfather. But Mohiam is most concerned with the potential outcome of the duel, which could prove to be "a major catastrophe for the Bene Gesserit breeding scheme." She realizes that "Two end products of this long and costly program faced each other in a fight to the death that might easily claim both of them. If both died here that would leave only Feyd-Rautha's bastard daughter, still a baby, an unknown, an unmeasured factor, and Alia, the abomination."

Paul is victorious; seeing the inevitability of the situation he has orchestrated, Mohiam compels Shaddam to give in to Paul's demands, allowing Paul to depose him and become Emperor in his place.