As a child Ganymede was enrolled into cadet training, that took place in a base originally constructed by the Titans and Eternals. It was hidden deep within one of the moons of Jupiter. She spent years training in myriad varieties of military tactics and combat styles. While in the academy she developed a friendly rivalry with a fellow cadet Persephone. Both warriors participated in the final campaign that drove Tyrant from the galaxy. Following Tyrants defeat the Spinsterhood placed its members in suspended animation chambers in their moon bases or in Ganymede's case, a chamber disguised as space debris floating in an asteroid belt.

Recently Tyrant's return reactivated the Spinsterhood. Virtually all of their suspension chambers had failed over the years and when Ganymede awoke the Spinster's computer network identified her as the sole surviving Spinster. Allying herself with the Silver Surfer, Ganymede stormed Fortress, Tyrant's planet-sized city-base, where the pair were captured alongside the Gladiator, Beta Ray Bill, Terrax, Morg and the Jack of Hearts; Galactus eventually arrived, forcing Tyrant to retreat. Ganymede took the depleted Jack of Hearts to the Spinstershoods's Jupiter moon base to recover and the pair almost began a romantic relationship, but she elected to maintain her religious vows until Tyrant's final defeat. Ganymede and Jack were ambushed there by Thanos and Terrax; the pair kidnapped Ganymede, though she soon allied her self with them when they opposed Tyrant. Leading them to the Fortress, Ganymede and Terrax battled Tyrant while Thanos raided his files; Jack of Hearts, with Genis-Vell, followed and aided them. Thanos revealed Tyrant's origin and that it had been Tyrant's creator Galactus, who had actually originally driven off Tyrant, but refused to reveal more and departed. Without Thanos' help, Ganymede fell before Tyrant; Jack transported her unconscious form to the Jupiter base.

Ganymede's recovery was interrupted by Persephone, Ganymede's former Spinster rival. Enigmatic alien Jakar sought Spinsters to aid him against Tyrant, and had resurrected Persephone's remains to this end. Ganymede joined Jakar and Persephone; with Jack, they were teleported to Fortress, where they stole Tyrant's power globe. Jakar teleported the trio back to Jupiter just as they confronted Tyrant, stealing the power globe for himself and fleeing. Stung by Persephone's contempt for her near-relationship with Jack, Ganymede partnered with Persephone, traveling to the Jubat system where Jakar had falsely led them to believe they could eventually ambush Tyrant. However, Tyrant was apparently destroyed elsewhere while the pair was at Jubat.