Born in Russia and trained by a European assassin’s agency from the age of 9; her parents were killed by a Russian politician. Her father was a journalist and by including the arms dealing and drug cartel laced within the Russian government, he angered said politician.This resulted in the murder of her father and the abuse and shooting of her mother; all whilst Katarina hid and tried not to watch. An old friend of her father's in Britain, Leo Simmonds, was her only familiar connection left and so living with him was the logical option.

He was engrossed in the art of training young assasins from a facility in London. She started to programme at the age of 10 and progressed quickly. Leo was never considered as a father figure in Katerina's life, but she still thinks highly of him and regards him more like her uncle. 

Katarina joined the agency at the early age of 15 and used her young age too her advantage; she got close to her targets before brutally eliminating them. She is determined, emotionless and has no sympathy for others (except Leo). But her main priority is to eventually avenge her parents, and she wouldn't let her love for Leo jeopardise that. She always puts the mission first in roder to perfect her skills and carry out her revenge. She speaks fluent Russian, English, German, Polish and Chinese Mandarin and is learning Czech. She is highly trained in martial arts, her preferred style being street fighting.