Kate Harker was a monster hunter and the daughter of Callum Harker.
Kate had blonde, shoulder-length hair which she used to cover the scar reaching from temple to jaw. She got this scar and another tear-shaped one in the corner of her eye from a car accident when she was younger. Furthermore, Kate has a sharp jaw and dark eyes.
For six years, Kate and and her mother lived in a house located at the eastern edge of the Waste. When Kate was a kid, she moved to Verity with Callum and Alice Harker. She wanted to go back to her home outside Verity and convinced her mum to take her. There was sabotaged by Sloan who killed her mother and damaged Kate's hearing by crashing the car. Years later, Kate was sent to five schools in six years. They were, as listed: two boarding schools in the first year, another in the second. A reform school for troubled teenagers for a year before she attended Wild Prior Academy (an all-boys school that Callum Harker had paid out) for several months. Lastly, Kate attended St. Agnes' Academy, a 'girls Catholic school, which she was expelled from after burning down one of the chapels (The Chapel of the Cross; the smaller of the two). She had to continually switch schools due to the disruptive behviour she displayed because she wanted to go back to Verity to be with her father.
Kate was fighting Alice when she died. She used the power she got from the Chaos Eater to help her fight Alice. When the power evaporated Kate pretended to give up, momentarily surprising Alice. She used that moment to run across the room to grab one of her iron spikes. Alice then came over to Kate as she drove the spike into Alice. At the same time Alice drove her fist into Kate's chest.
Later when August went to go find Alice he found Kate laying on the floor, her hands covering the wound Alice gave her. Kate knew she was dying so she let August take her soul asking if the souls he took stayed with him. He responded "I don't know." Kate stated the she wishes that he could lie sometimes. Before August can say anything else Alice's wound kills Kate letting August take the last of her soul.
Kate and August originally got to know each other at school. Kate first knew him as Freddie Gallagher, only knowing him as August Flynn after she figured out he was a Sunai. She intended to bring him to her father but eventually decided against it after August saved her from a group of Corsai and Malchai sent by Sloan. They then flee the city becoming very close friends. A romantic relationship is hinted at, but not developed, during Our Dark Duet. August was very distraught after Kate died.
Callum was Kate's father. They had a rocky relationship on the fact that Callum did not want Kate in Verity. He eventually took pride in her giving Kate a silver medallion. When Kate found out that Callum was working with Sloan she attempted to kill him. August stopped her saying that he wasn't worth it, and then reaped Callum's soul.
Sloan hated Kate. When Kate returned to Verity, Sloan teased and scared her. He made it very clear he did not want her back in Verity, that she would be better dead. He mostly called her "Little Harker" saying she would always be little Katherine Harker to him, never amounting to her Callum.
Alice and Kate hated each other immensely. Alice continually tried to kill Kate eventually succeeding. Alice was the monster that resulted from Kate's sins. Because of this, Alice looks like Kate in a funhouse mirror, similar, but wrong.
Alice Harker was Kate's mother. She was close to Kate and died after Sloan crashed their car. Kate blames herself for her mother's death, since she was constantly begging her mother to leave. Her mother died in the trip that Kate had always begged for. This haunts Kate later in her life and is one of her greatest regrets.