Janess was conceived and born when Murbella and Idaho were held captive aboard a no-ship-prison which was located on the Bene Gesserit capital world of Chapterhouse. Upon being born, Janess was whisked away from her parents to be brought up inside of the Sisterhood. Contrary to many Gesserit births, Janess was aware of her parentage; and was allowed to muse on, and even visit her mother.
As great events unfolded with the Return of the Honored Matres, and the beginning of the time of Kralizec; Duncan, Sheeana, and the rest of its' crew and captives, escaped aboard the no-ship, now christened the Ithaca, and folded space into another universe to escape the unknown Enemy, Daniel and Marty. Idaho and crew would be "lost" for over 26 years, with Janess and Duncan being separated as daughter and father for that entire time.
Leader of the Valkyries
Concurrently, Murbella became leader of the combined Matres/Gsserit group, The New Sisterhood; and after Janess became a Reverend Mother, Murbella appointed Janess commander of her para-military group, the Valkyries. Janess continued her training in being a Swordmaster of Ginaz, just as her father was, as well honing her skills of the Valkyries.
Janess quickly proved herself as Murbella ordered her to wipe out the rebel Matres factions that existed through the galaxies. First eliminated, were the rebels on Chapterhouse itself. Second, Janess was able to quickly take Gammu from the Matres, and killed many Matres leaders personally. As a last and great test, Janess Idaho led the attack on the final rebel Matre stronghold on Tleilax. Using stealth, secrecy, and then overwhleming force, the Matre Superior, Hellica; found herself surrounded in Bandalong by Idaho's forces. As Murbella joined her daughter to personally kill Hellica herself, Hellica changed back into an Enhanced Face Dancer before Janess's and Murbella's eyes.
After the defeat of the last rebel Honored Matres stronghold, Janess was promoted to Supreme Bashar of all of the Sisterhood's forces; as the onslaught from the final and great Enemy, now realized to be Thinking Machines, started to begin.
As her mother attempted to unite all of man-kind to face the Thinking Machines in a consistent, organized manner; Janess was her mother's invaluable counsel. She supported her mother's journey to The Scattering space, to witness first hand the devastation wrought by the Omnius Scourge. As the plague and machine armada invaded planets of the Old Imperium, Janess was on the front line as she tended to the sick and those who died.
Janess traveled throughout the Old Imperium and encouraged all the fragmented parts of humanity to join together to face the forces of Omnius and Erasmus together. She dispersed her mother's newly created starships and Obliterator weapons throughout the core worlds of human-kind.
The Day of Kralizec
As the day of Kralizec began, Murbella had her in a separate ship in her armada above the skies of Chapterhouse. It was Janess that first discovered that the ships and weapons that had been produced by the foundry star-ship yards of Ix had been greatly sabotaged, as neither functioned when humanity fired upon the Machines.
The day of Kralizec unfolded as the Machine ships attacked, but the Oracle of Time/Norma Cenva appeared with hundreds of Guild Heighliners, and completely destroyed the first wave of machine ships. Idaho and the human fleet were equally astounded when the Machine ships just stopped functioning and drifted aimlessly over Chapterhouse. Lastly, Janess found herself completely dumbfounded when her mother's ship was whisked away by the Oracle's Guild Navigators, and a few hours later, her mother returned with her father, Duncan Idaho.
To Janess's great surprise, not only was the Man/Machine war completely over, and her father alive, but he was also the Ultimate Kwisatz Haderach. Janess was filled with happiness, as it was discovered that now man and machine would live in complete harmony, with her father being both the new Evermind, as well as the super-being of mankind.