In her first appearances she was depicted as a character completely devoted to the Joker, totally oblivious to his psychotic nature and obvious lack of affection for her; this characterization has remained more or less consistent throughout her subsequent appearances.
However, whilst they are distracted by his speech, Waller's agents slip behind and capture her.
She murdered an unspecified number of staff and security guards; mostly with her handgun but some were killed by mallet.
Shortly after this, Poison Ivy breaks into Harley's cell and attempts to kill her for her betrayal, but instead offers to free her if she helps kill Catwoman, who had left both of her fellow Sirens behind in Arkham.
However, when John offered to help her find the mole, she dismissed him and asked to talk to Bruce.
She, Bruce and John later arrive as their men prepare to execute Catwoman in one of Freeze's cryogenic chambers.