DC Comics released the American comic book series Gotham City Sirens, which was written by Paul Dini and illustrated by Guillem March. Catwoman, Harley Quinn, and Poison Ivy are the three most well-known female villains in Gotham City, and together they are referred to as the “Gotham City Sirens.” June 2009 saw the release of the first issue of the series as part of DC’s Batman: Reborn relaunch, which included all of the character Batman’s comic book titles.

When Catwoman fights a new villain named “Boneblaster”, it is revealed she still has physical limitations from her ordeal in “Heart of Hush” and is nearly easily beaten by the two-bit thug. However, Poison Ivy arrives to save Catwoman and offers her to return to her new hideout, which is actually the hideout of the Riddler, whom Poison Ivy has seduced and drugged. Catwoman discovers Harley Quinn is also living with them, and proposes that the three women join together to protect one another as a team, but first Harley Quinn and Poison Ivy want to know who Batman really is.

When Poison Ivy uses a truth serum powder derived from plants, Catwoman reveals that she cannot because Talia, Ra’s al Ghul’s daughter and leader of the League of Assassins, used mind control techniques to prevent Catwoman from ever forcefully revealing his identity as Bruce Wayne. Talia taught Catwoman a meditation technique so that any sort of mind-control, such as Ivy’s spores, will not affect her.