Eve was the daughter of Xena (Lucy Lawless), by way of a miraculous conception with a deity called the God of Light. This came about when Xena chose to save her former enemy, Callisto (Hudson Leick) , from eternal suffering. The redeemed spirit of Callisto allowed Xena to conceive a child, who was selected to be her reincarnation.
Before her birth, Xena's unborn daughter was prophesied by the Fates to become the Bringer of Twilight, the human who would bring about the end of the rule of the Olympian gods. As a result, Zeus attempted to kill Xena and her child before this happens, but was thwarted by his son Hercules.
The gods under control of Athena (Paris Jefferson) continue to come after Xena and Eve, and therefore, Xena fakes her death along with Gabrielle (Renee O'Connor). However, Ares (Kevin Smith), believing them to be dead, buries them in an ice came. In the meantime, 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. Eve is now a brutal warrior known as Livia, the Champion of Rome. She is the protegee and lover of Ares, but is intending to marry Augustus and thus become the 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. She feels conflicted when Eve murders Xena's old friend Joxer (Ted Raimi).
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 God of Eli 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, bringing about their own demise when Xena goes up against them with her newly acquired power. Ares and Aphrodite survive, having remained neutral during the ordeal. However, Ares gives up his powers and immortality to save Eve and Gabrielle.
After the Twilight of the Gods, Eve travelled with Xena and Gabrielle. As such, she appears in the first four episodes of season six. According to an interview with Adrienne Wilkinson, the episode "Coming Home" took place a year after the events in "Motherhood".
After "Who's Gurkhan?" Eve apparently returned to Rome, though no explanation was provided for her absence. In fact, while Xena seemed to know where Eve was, Gabrielle didn't, as seen in "The God You Know" where Gabrielle seems surprised to learn Eve is in Rome.
Eve challenges the emperor, Caligula in "The God You Know" in regards to his slaughter of the Elijans. She is nearly killed by Caligula, but Xena arrives in time to defeat him and save Eve.
Eve is seen briefly in "You Are There" being interviewed by a news reporter Nigel.
Eve's final appearance in the series was in the episode "Path of Vengeance" in which she returns to the land of Varia's tribe of Amazons in order to atone for her attack on them six years prior. Varia, now leading the multiple Amazon tribes that have gathered from around the known world, captures Eve in order to make her stand trial. Marga had apparently banished Eve after "Coming Home" with the threat of death if she returned. Varia, having lost her little sister at Livia's hand during the attack on her village, is after Eve's life.
It is revealed in this episode, that the Amazons she captured as slaves (as stated in "Coming Home"), she had tossed overboard with their shackles still on when she was unable to sell them to Gurkhan.
Gabrielle challenges Varia for leadership of the Amazons in order to save Eve's life when she is found guilty, but loses. Xena challenges Varia to a fight before she can execute Eve, and in doing so, she shows Varia that she has become like Livia, which leads Varia to stop her actions, and pardon Eve (stating Livia is dead).
At the end of the episode, Eve parts ways with Xena and Gabrielle, heading to China to continue to spread the message of Eli. Xena offers to go with her, but Eve states she needs to do it on her own, and departs.