The girls were born in Hungary, in the year 1396. They lived with their mother, aunt and grandparents at the family home (their father is never mentioned). In 1402, when Selene's nieces were only six years old, they were murdered by the Vampire Elder Viktor, who killed their entire family - save for Selene - to prevent the secret location of William Corvinus' prison (which Selene's father had constructed) from getting out, after the infamous Lucian unknowingly obtained one of the keys.
Selene states that after being woken by her mother and sister's screams, she ran to her nieces' room, only to find she was too late. Selene says her nieces were "butchered". Viktor spared Selene due to her resemblance to his deceased daughter, Sonja, and told her that Lycans had killed her family. This prompted Selene to become a Death Dealer to hunt down Lycans and avenge her family.
Selene mentions her nieces to Michael Corvin, after he asks why she hates Lycans so much. Selene appears to still be affected by her nieces' deaths centuries later; despite being a rather stoic and even cold person, she becomes upset when speaking about her nieces. Michael, too, is affected; uttering a horrified "Jesus Christ" after hearing of the brutal nature of the little girls' deaths. After learning that Viktor was the real culprit, Selene turns on him and kills him, thus exacting some form of justice for her family.