Ivy Thorburn is the daughter of Bradley Thorburn and his wife, as well as the sister of Blake Thorburn, conceived some time after Blake ran away from home. Later on it is revealed he is a vestige and Rose is her actual older sister.
An infant with wisp-thin blonde hair.
As an infant she hasn't developed much of a personality, although she seems intellegent for her age as she was able to identify Blake as an Other when he was inside the TV.
She first appears in the story in the opening chapter, at the death bed of her grandmother, where all of her family had gathered. Her brother arrived after being missing for three years after running away from home, but it's doubtful she recognized him due to her age. Later on she appears sleeping when held by her sister at her mother's behest.
During the Malfeasance storyline she was able to see Blake while he was in the reflections, identifying him as a "Black line face man" and "Bad Man", scaring her as he broke the windows and feeding off of her fear (although he felt bad about it) until they took her out of the house after her cousin, James Thorburn, was hurt.