Nikolaos was turned into a vampire when she was about 12 years old. She retained her young body and voice even though she has lived for over 1,000 years. She is described as sounding like Shirley Temple... when she isn't angry. She is master vampire of the city of St. Louis, Missouri.
She blackmails Anita Blake into investigating a series of vampire murders that have taken place in St. Louis.
Since Nikolaos has lived so long, she has gained more powers than younger vampires. Other than having the normal vampire abilities (which are much stronger than other master vampires), she can also levitate. Nikolaos's animal to call is the rat, and therefore the wererat.