|Sophie "Fee" Susskind is Zach's twin sister. When the Susskind family split apart, Zach doubled down, doing his best to take care of his younger sisters while their mother worked. Fee on the other hand began lashing out, causing problems until she was eventually sent to boarding school out of a lack of other options. Because of this, she is absent for the beginning of book. When she does come back, she's revealed to share her brother's ability to see through illusions and becomes immediately cautious of Lucibel and Tristan, giving them another thing to worry about as they attempt to save the world.