Sera Froste is Dak Smyth's best friend. She is a genius in science, and has a particular love for physics. She experiences Remnants that are said to be caused by the Great Breaks in History, and are related to Sera's parents, whom she never really knew. In the original timeline, she lives with her Uncle Diego.
In The Trap Door, Sera gives the chain necklace from the previous book to Thomas Garret, so he can continue to support the abolitionist cause. Earlier in the book, Sera also made a mistake with the Infinity Ring, taking Ilsa and herself to the Cataclysm, although part of the subsequent events in the time period were blocked out of her memory.