Nyx is Theo's old paramour from when he used to teach at the Academy at Mytros.
Theo broke off their relationship when his wife and children disappeared.
Despite the difficult situation, Nyx was the only one to believe Theo about his family and spent the time since he left the academy trying to research their existence. Unfortunately, her research led her to the Lady of Coins and resulted in her own disappearance and petrification. Luckily, the Oracle's Chosen saved her before she could be spirited away to Hexia.
Nyx works at the Hall of Heroes at the Academy, as well as being a poet in her spare time.