Later novels deal more heavily with Cal's attempts to balance the dark nature of his father's race with his impulse to protect and defend others against the supernatural.

"[5] Cal inherited his Greek-Romani mother's raven hair, but has the pale skin of his father.

As their mother was neglectful and really didn't pay much attention to them, Niko took to looking out for his younger brother at a young age.

Considered the "practical" one of the pair, Niko is calm, and enjoys meditation and natural foods.

Having been alive for an extremely long time, he has made his way through history, and crossed paths with the likes of Caligula, Salome, Bacchus, and Sigmund Freud to name a few.

Her romantic attraction to Caliban was never fully reciprocated, due to Cal's fear of how his Auphe heritage would affect any relationship they could have.

[12] Sales for the series have been good, with several of the novels placing on The New York Times Best Seller list for mass market paperbacks.