Elysium is the living will of the magic sword Soul Calibur, just as Nightmare represents its polar opposite, the sword Soul Edge. Its fiirst appearance in the Soul Calibur franchise came in Soul Calibur V. It had not appeared previously because the wills of its prior wielders were in tune with that of Soul Calibur. However, as hinted at in several characters' endings in Soul Calibur IV, Soul Calibur is not "good" and Soul Edge is not "evil"; they merely represent order and chaos. This has extended to the point where Soul Calibur has become unsatisfied with the brief periods of relative order created in the past through being wielded by a good-aligned hero who strikes down Nightmare. Elysium has decided that the best way to create peace is to defeat Soul Edge and use its power to turn all living things into crystal, leaving the Earth barren and lifeless, and transforming it into a "utopia of order".
Elysium appears for the first time when it makes contact with Patroklos Alexandra, taking on the appearance of his mother, the late Sophitia Alexandra. It leads him along, providing advice to further Soul Calibur's plans before ultimately taking over his mind and leading him to murder his sister Pyrrha, who had been possessed by Soul Edge. At this point, Soul Calibur successfully creates its desired utopia.
However, the mysterious Edge Master somehow makes contact with Patroklos's consciousness and sends it back in time to his body at a point before he was betrayed by the sword. Given this second chance, Patroklos refuses to become Soul Calibur's slave. With its plans at an impasse, Elysium turns on Patroklos and confronts him within his mind as the final battle of Soul Calibur V's story mode.
As Elysium engages in this battle, intending to kill Patroklos from within and take over his body, it hides Sophitia's face with an opaque visor and sprouts wings from its back. However, despite its incredible power, Elysium is defeated by Patroklos. Left in a weakened state, it is forced from his mind.
Patroklos and Pyrrha, who moments earlier had been freed from the weakened Soul Edge's grasp, work together and impale Soul Calibur with Soul Edge, causing both blades to break once and for all.
In the story mode, since Elysium is based on Patroklos's memories of his mother, it uses Sophitia's sword-and-shield battle style when Patroklos fights it. After it is unlocked for use by the player, its fighting style is randomized in a manner similar to Edge Master, though Elysium will only take on the fighting styles of female characters.