Kallista was born on Arkania to Jedi parents along with her twin sister. After a  situation in a Cantina on Tatooine, a bounty was placed on her father's head in their system. Tor-Mec removed Kes and their twin daughters, Kallista and Kalleer, to Coruscant to live. The girls has just reached their fifth birthday when Tor-Mec's padawan, a Force-sensitive girl by the name of Vash, turned to the Darkside and took Darr with her. No longer seeing the need for a master, Vash fled Coruscant and went on to take Sith apprentices of her own.

Meanwhile, Kes tried everything to draw her mate back to the Lightside. Nothing worked. Enraged by her attempts to take away his newfound powers, Darth Torment retaliated and stole away with the younger twin, Kalleer, to Yavin IV where he proceeded to train his daughter in the Darkside.

Kallista, remaining with her mother, was moved back to Arkania and trained to be a Jedi. Kallista soon became obsessed with locating her twin sister, eventually using the Force to direct her. At the age of sixteen, she slipped away from their mansion on Arkania and hitched a transport to Yavin IV.  After a day or two of search, the Force directed her to a temple not far from the moatbound sanctuary of the wraith, Exar Kun. There she found Torment and her twin, now going by Darth Killeer. Torment attempted to corrupt Kallista, and she, furious at all of her father's past and present misdeeds, slaughtered him. Killeer fled and a brief stint with two Sith by the names of Sidious and Maul led her further into the Darkside of the Force.

Kallista, afraid to return home to her mother bearing news of what had transpired, sought a new master to continue her training. She found a Jedi master by the name of Gevnos on Coruscant. But Genvnos was far from what he seemed. Vash, Tor-Mec's fallen padawan, had learned of her old master's slaughter by Kallista and became bent on corrupting the Jedi woman as she had corrupted Tor-Mec. To execute this, she insinuated herself into Gevnos' mind and beckoned to his weak morals. Easily he became the dark pawn of Vash, and thus, Vash accomplished her plot through Gevnos to sway Tor-Mec's daughter to the Darkside, unbeknownst to Kallista herself. Kalli, under Vash's tutelage, became quite a fierce Sith apprentice, earning the name Darth Siryn.

In no time, Kallista was Vash's devoted apprentice, blissfully unaware that her Mistress was the one who had orchestrated her fall from the Lightside. Gevnos, resenting Vash's affections for her young apprentice and the notion that Vash had used him, poisoned Vash and bound the unwilling Kallista to himself as an apprentice. Kallista retaliated by slaughtering Gevnos as she had her father. She was twenty at the time.

Now alone, her Mistress pyred, Kallista commandeered Vash's personal ship, the Chaos Warrior and made her way to the outer rim, landing on Tatooine to refuel. She paused breifly in the notorious Mos Eisley Cantina for a drink before she continued on her way. It was there she met Darth Sinn. He took her in as an apprentice and trained her. A train of events still a mystery to Kallista, saw Sinn returned to the Lightside. Unwilling to leave her new master, and tormented by the pain of past deeds and events, Kallista allowed herself to be restored to the Lightside as well. She retook her name of Kallista Stormbringer and remained under his tutelage until just before his unfortunate death.

Kalllista was again on her own, and resolved herself to return to Arkania and her mother to patch things up. Kalli returned to her native planet and reunited with her mother after five years. It was a happy reunion, and she remained on Arkania with Kes for almost a year before another set of events would yet again haunt the young Jedi woman.

Kallista had been residing with Kes Stormbringer for almost a year, and had Impressed two Arkanian dragons, named Chaos and Darkmoor, before they both felt a sudden darkness descend on their beloved homeworld. Darth Killeer had returned home. In despair over the death of the Sith she had loved from a distance, Killeer had forced herself back to Arkania. Kes, seeing what she must do, expended all of her power over the force in an attempt to restore Killeer to the Light path. She was unsuccessful, and lost her life in the effort.

Killeer and Kallista mourned their mother together, not as Sith and Jedi, but as sisters. The raging anger and despair that wrought Killeer was slowly calmed by the time she spent with her sister. The Sith even allowed Kallista to teach her in some of the Jedi ways she had been denied by her father. Shortly, it was as if the twins were no longer default enemies, but simply the young, Force-wielding sisters they had been before events had ripped them apart.

Killeer eventually became restless and departed Arkania with a promise Kallista that she would be alright, and she was no longer the angry, destructive Sith she had once been. Kallista knew that the Darkness in her sister would never be tamed as Killeer had promised, but let her go, knowing the younger twin could hold her own. Kallista corresponded with the Jedi Council on Coruscant and began running diplomatic negotiations for them. However, a trip to visit her sister wouldn't allow her to remain a Jedi for long. Rather, Exar Kun wouldn't. She dwelled with Killeer and the wraith, under his influence, for about a year before both twins were sent off on separate missions.

It was that mission that  led Kalli to a place that had been the starting point for trouble a few times in her life. The Mos Eisley Cantina. Again, it was there she met someone who would change her life. A Jedi. Rane Gaxen, who offered to help her find Killeer. She had no idea why a Jedi would even consider helping a Sith, but she had decided at that point to give up Kun's "mission" and find Killeer, wherever she had gone. She agreed, and true to his word, he helped her find Killeer. She was somewhat miffed when he wouldn't accept payment for his help.

She ran into Rane again back on Yavin IV, where in an epic tale, Exar Kun posessed the body of Feln, Mace Windu's apprentice who had accompanied Rane. Kun battled Rane, as well as the Stormbringer twins, but the Jedi escaped, leaving Kallista miffed again, but this time about that pang of guilt that was nagging at her for attacking the person who'd helped her find her twin. Kun, seeing that she had feelings for the Jedi and convinced she had let him get away because of them, sent Kallista on another mission that would prove her loyalty to Kun and deal the Jedi Order a crippling blow. She was to go to Coruscant and slaughter as many Jedi as she could.

Kallista went, with no small amount of fear for what Kun would do if she refused, and inflitrated the Temple on Coruscant. Fortunately for her (and unfortunately for Kun and the mission) she failed to factor in the fact that her presence in the Force would be glaringly obvious to someone who'd encountered her before. Someone like Rane. Little surprise that it was he who found her skulking through the Temple, intent on massacring some Jedi in their sleep. She wanted to fight him, he wanted to talk her out of it. In the end, he brought her mother's sacrifice and hopes for her daughters into the equation, and stunned, Kallista left, completely ashamed of herself for turning away from what her mother had wished for her. She didn't realized she'd dropped her saber.

Kallista returned to Yavin IV, and prepared to face Kun's wrath when she reported that she'd failed. It was sheer luck that Rane had followed her to return her saber and arrived just as Exar was about to show her just how much he appreciated her failing. Even Killeer was convinced Kallista's loyalties were with the Jedi knight, and fought Kallista. Killer had Kun's power behind her and Kallista didn't have the energy to fight both of them. But she did make a decision. If she was going to die, it wasn't going to be as a Sith. Kallista followed her mother's footsteps and focused her last remnants of will and energy and dragged herself away from the Dark Side. Rane showed up at that very moment and led her off to his ship, taking them both away back to Coruscant.

This would be the last time Kallista would defect from either side, and from the moment the Council reluctantly allowed her to return to her status as a Jedi knight, she practically threw herself into her Jedi training. It was also then that she realized what had been happening all along. She was very much in love with Rane.

Months later, Kallista was made a Master by the Jedi Council. This caused some friction in the relationship, and consequently, Rane left to seek out a disturbance on Derra IV. Kallista followed. It turned out that was exactly what the cause of the disturbance was hoping for. It happened to be Drakh, Kallista's former lover and another student of Darth Sinn's. Having wounded Rane and imprisoned him behind transparisteel, he ended up fighting Kallista and flash-blinding her so he could kill Rane unimpeded. His plans went sour when Rane, in an incredible manipulation of the Force, was able to connect with Kallista and act as her eyes. Kallista made short work of ending the Sith's life. Upon returning to Coruscant, the Council agreed that the events had proven Rane was ready to take the Master trials.