Pyrrha Alexandra is the daughter of Sophitia Alexandra and the sister of Patroklos. She was kidnapped from her family by Tira at a young age; although the following seventeen years are murky, when Soul Calibur V's story mode begins, she has been trained in the Athenian-style sword-and-shield form of combat favored by her late mother Sophitia and aunt Cassandra, and believes Tira to be a friend. She has also become "malfested," or partially possessed by the evil corruption of the cursed sword Soul Edge. It is Tira's wish to see that Pyrrha is sufficiently corrupted so that she will make a perfect vessel for the cursed sword.
Although Pyrrha is eventually reunited with her long-lost brother Patroklos, he flees her side after discovering her malfestation, which overtakes her as she unleashes her dark power to protect him from Nightmare. Giving in to despair, she is guided by Tira to a battlefield where, with Z.W.E.I. having finished off the current form of Nightmare, Pyrrha is able to claim Soul Edge and become its new puppet.
After her defeat at the hands of Patroklos, wielding the Soul Calibur, she awakens to find her brother frozen in crystal; a punishment rendered by Elysium. Realizing her mistakes, she manages to assert herself and take hold of Soul Edge without it consuming her in order to break Patroklos free. Reunited and no longer controlled by the swords, they smash the Soul Calibur and the Soul Edge against each other, shattering the blades and ending the eternal struggle between the swords, if only for the time being.
The standard form of Pyrrha wears light-colored clothing and wields her mother's sword and shield. Her alternate form, Pyrrha Omega, reflects her corruption at the hands of Soul Edge. In this form, Pyrrha's clothes are darker, her eyes glow red, and her right arm shows signs of mutation similar to that of Nightmare.
Pyrrha's fighting style is based on that of her aunt, Cassandra Alexandra. In her Omega form, she fights using a modified version of her standard fighting style. This is in contrast to Alpha Patroklos, who fights using a style completely different from that of his standard form.