Eve is the daughter of Xena, born of a miraculous conception (there was no father) after Xena and Gabrielle encounter a deity called the God of Light. When Xena chooses to save her former enemy, Callisto, from eternal suffering, the redeemed Callisto's spirit is somehow transferred to Xena to create a child that shares qualities of both Xena and Callisto. Eve's exact nature is ambiguously defined in the series, and several theories exist about the role played in her conception by the God of Light and his servant, the Archangel Michael.

Before her birth, Xena's unborn daughter is prophesied by the Fates to become the Bringer of Twilight, the human who will bring about the end of the rule of the Olympian gods. Zeus attempts to kill the child (and her mother) before she is born, but is thwarted by Hercules, who kills him with a rib of Cronus. Xena delivers the baby with Gabrielle's help in the shade of a tree, moments after Zeus's demise. Xena names the girl Eve, a name that her deceased son Solan suggested upon seeing him in the underworld. Meanwhile, Athena becomes the leader of the Olympian gods, and they continue their ceaseless persecution of the infant Eve. Driven to desperation, Xena and Gabrielle fake their own deaths and that of Eve by staging a fatal crash, then taking a sleeping draught in a manner similar to the ploy in Romeo and Juliet. They intend to awaken shortly afterwards, but the plan goes awry when Ares, believing them to be dead, buries Xena and Gabrielle in an ice cave. Eve remains in the custody of Xena's friend Octavius, who proceeds to take her to Rome and sends her to the provinces to be educated.

Twenty-five years later, Xena and Gabrielle awaken to discover that Octavius has become the Roman Emperor Augustus Caesar, and Eve is now a brutal warrior known as Livia, the Champion of Rome. She is the protege and lover of Ares, but is intending to marry Augustus and become Empress. Xena sets about trying to stop her daughter from massacring innocent people, and in the process inadvertently exposes Livia's identity to the gods, who resume their persecution of her as the Bringer of Twilight.

Livia is reformed when Eli's spirit shows her various moments of Xena taking care of her when she was a baby, and learns that her mother truly did care for her. The reformed Livia once again takes on the name of Eve, and intends to become the Messenger of Eli, who taught pacifism and independence from the Olympian gods. While Eve is initiated into the sect of Eli, the Archangel Michael gives Xena the power to kill gods as long as Eve is alive. This development causes the Olympians to redouble their efforts to kill Xena and her daughter, ironically bringing about their own demise when Xena goes up against them with her newly acquired power. Ares and Aphrodite survived, having remained neutral during the ordeal. However, Ares gave up his powers and immortality to save Eve and Gabrielle.

After the Twilight of the Gods, Eve sets about trying to atone for her past, but the character appeared infrequently in subsequent episodes.