"Boy" is Lucille Butler, an officer of the New York Police Department. Her brother Martin, also a police officer, was working for The Conspiracy, a fact known to a third brother, a gang member named "Eezy D", but not to Lucille. In a battle against the Outer Church, Eezy D is killed and Martin is taken prisoner. Lucille's life is saved by her partner, although he cautions her that the Invisibles will be looking for her.
Hoping they will help her rescue her brother Martin, Lucille allows herself to be recruited by the Invisibles, who give her the code name "Boy". Boy becomes somewhat of a mentor to Jack Frost, and their relationship eventually develops into a romantic one. Boy later steals an artifact known as the "Hand of Glory" and goes searching for the secret prison camp in which she believes Martin to be detained. Boy is abducted by the Outer Church and informed that her identities as "Boy" and "Lucille Butler", among others, were entirely fabricated, and that she was secretly an operative sent to retrieve the Hand of Glory for the "Lost Ones", who plan to use its power to destroy the sun.
At the command of her new masters, Boy is about to kill King Mob when it is revealed that the ostensible agents of the Outer Church are in fact members of Invisibles Cell #23, who have been deprogramming Boy to defuse a previous hypnotic suggestion from the real Outer Church. When she realizes that there is no way to save Martin, and there never had been, Boy quits the Invisibles forever, and she starts a new life in New York, where she later has a child.