Harley Quinn

About her
Dr. Harleen Frances Quinzel, also known as Harley Quinn, first appeared in the Batman: The Animated Series episode "Joker's Favor" where she served as a humorous female sidekick to the Joker. In her first appearances she was depicted as a character completely devoted to the Joker, totally oblivious to his psychotic nature and his obvious lack of affection for her a characterization that has remained more or less consistent throughout her subsequent appearances. Her name is a play on the word 'harlequin'.

In the game
In Marina's game, she was seen in another room waiting for Marina but her scare mouse