An Ember in the Ashes
Cook is one of the supporting characters in the story. Cook is a slave for the Commandant and has a disfigured face from the Comandant's abuse. She made explosives for the resistance before she was a slave working for the commandant. She also knew Laia's parents (she did not like the lioness) It seems that the Cook had been betrayed by the resistance. Cook helped Laia save Elias from being executed but she would not want to escape from slavery herself.
A Torch against the Night
Cook actually did escape from the Commandent and she goes after Helene she subdues her and gives her a hint as to where Elias will be, but she threatens Helene that if Laia is harmed there will be consequences