| The subject of this article is non-canonical.|
While created as part of licensed material, it has not been confirmed as part of the "real" Buffyverse continuity.
Diana was a Slayer from Roman antiquity.
Diana was called as the Slayer in 38 A.D. at the age of 15. She lived in Rome with her watcher, Aulus. Diana's relationship with her watcher was contentious and tense at best; they respected the roles played in each other's lives but Aulus did not approve of Diana maintaining a friendship with Helen, and Diana refused to give up her relationship with Helen.
Helen and Diana were as close as sisters, even though, Diana did not disclose her identity as the Slayer for awhile. Helen found out about Diana's secret identity one evening while they were out walking and ended up being attacked by vampires. Initially shocked, Helen agreed to keep Diana's identity a secret.
This promise soon was broken as Helen accidentally slipped and revealed to her lover, Julian, the true identity of Diana being the Slayer. Unknown to Helen, Julian was a manipulative and cunning vampire who worked for the local vampires and he betrayed Diana to them. One evening, vampires attacked Diana in the hopes of eliminating her, but Aulus, perhaps showing the first sign of kindness and fondness for his charge, named Helen (who was visiting at the time) as the true Slayer to spare Diana's life.
Now a prisoner, Helen was forced into a gladiator ring to fight vampires and other creatures up to 10 times her strength and size for the amusement of the spectators. It soon became clear Helen was not the true Slayer and she was turned into a vampire by Julian so they could be together forever. Eventually Diana, now in hiding, discovered the whereabouts of Helen and vowed to free her friend. Unknown she had been sired, Diana found Helen and soon a fight between the two former friends erupted. Helen, driven by intense anger and her new found vampiric strength, managed to overpower Diana in battle and killed her by snapping her neck. It is not clear if Diana died as a result of being overpowered or if she gave up due to the guilt over what happened to Helen.
In 41 A.D. a new Slayer was active in Rome and sought to avenge Diana's murder; however Helen and Julian were at this time seeking to raise Meter, the goddess of destruction-a ritual that required the heart of the Slayer and the ashes of Emperor Caligula. This new Slayer managed to keep the urn with Caligula's ashes safe from the vampires, but lost her own life in the process.
Helen developed a deep hatred for Slayer's and killed every Slayer she ever encountered over the centuries.