Catwoman, distracted by the loss of Bruce Wayne, was taken down in Gotham City by Boneblaster, a new super-villain trying to make a name for himself by killing big name vigilantes. Due to her recent encounter with Hush, Selina was not herself in peak physical condition. She was saved by Poison Ivy, who then brought Selina back to her hideout, which was actually the apartment of the Riddler, whom was being drugged by Ivy. Harley Quinn is also living there with Ivy. When Boneblaster attacks again, having followed them to the general area, and then locating the house with plants. After the three ladies defeated Blaster (leaving him to be beaten by the Riddler, whom he had also attempted to kill) Selina suggests they form a team.
After a consult with Zatanna to find out what was really wrong with Catwoman, Poison Ivy and Harley Quin agreed as, "positive female reinforcement", but then asked a simple question to Ms. Kyle: Who is Batman? Ordinarily, Catwoman would have refused, but she was being forced to tell the truth by toxic plants wielded by Ivy. Using skills taught by Talia Ghul, Selina was able to convince them stating that everyone who had ever taken the cowl and pretending that it was a league of Batmen. Quinn and Ivy were satisfied, and accepted her offer of a team.
Gotham City Sirens was created by Paul Dini (June 2009) as part of the Batman: Reborn line up.
Catwoman (Selina Kyle)
Harley Quinn (Harleen Quinzel)
Poison Ivy (Pamela Isley)
The trio are known for being part of Batman's rouge gallery of villains. While the trio are still considered to be criminals, they engage into hero activity from time to time.
Major Story Arcs
Hush and the Joker
Later, on an outing by herself, Harley Quinn was confronted by someone appearing to be Bruce Wayne and abducted. Little did Harley know, Bruce Wayne was none other
than the sinister Thomas Elliot, better known as Hush. Attempting to get help from the Riddler, Catwoman and Poison Ivy ask for the Riddler's aid in the situation, Seemingly, he is not not able to help the two Sirens. Both ladies furiously leave Mr. Nigma.
After joining up with Batman to bring down a crime, Nigma notices a TV show broadcasting of Harley and Elliot leaving in a car together and tips off the sirens. Meanwhile an angry Joker views the same tabloid TV show broadcasting Harley and Elliot's sighting. Betrayed, Joker sends his minions after the couple. As Harley gets to know "Bruce" better, Elliot looks for ways to murder Harley and pass it off as an accident.
Suddenly, a Joker -blimp appears with two men appearing to be Joker henchmen. They attack Harley to try and kill her, inadvertently preventing Hush from carrying out his plan. Ivy and Catwoman arrive and help, but then retreat at the fight gets too dangerous to them and the bystanders. Hush has the opportunity to shoot any one of the Sirens and somewhat convincingly pass it off as self-defense, but instead he shoots down the blimp and takes the glory for capturing Joker's minions.
Later after the girls discuss the recent events, as Harley finally proclaims to swear off the clown prince, a Jokermobile crashes into their home setting off an explosions. Ivy protects them with vines, and the three decide to take down Joker once and for all. They go to the warehouse where Joker kept equipment like the Jokermobile. After entering, they meet someone who attacks them and appears to be Joker. Harley tries to warn them that he is not, in fact, "Mr. J," but she is stopped by Ivy who believes she has switched to Joker's side again. The girls are defeated and the man is about to kill Quinn, but
Harley insults him so he will finish her off more elaborately after explaining why (Harley does this simply to bide time). The man reveals himself to be Gaggy, Joker's original sidekick, and he drags her off to a secret storeroom. Ivy and Selina pursue him, but are trapped by spiky walls that begin to close in the attempt to crush them.
Gaggy explains to Harley he wants to kill her because she stole his place as Joker's sidekick. Ivy manages to delay her death by using her last available vines to slow the closing walls;
Catwoman then calls Jenna Duffy aka the Carpenter to help get them out. They escape and arrive just in time to save Quinn. The Sirens then battle Gaggy and strap him to a Joker-rocket and shoot him off into the air. They then return to their home (which has been newly renovated by Duffy); unbeknownst to them Gaggy survives the explosion and crash and vows revenge on Harley. Harley decides that she is done with Joker because she has become so pathetic pining for him, but then says she might change her mind.
When Catwoman, Poison Ivy and Harley Quinn discover a body literally dropped into their home and previously planted with evidence that it was the Sirens that killed her, the girls enlist the help of the Riddler once again to find the real person trying to frame them. When the Riddler investigates the girls' new hideout, he is suddenly ambushed by Doctor Aesop, who was thought to be dead. It was revealed that he was the real culprit. Luckily, the girls managed to save the Riddler before Doctor Aesop could kill him and turn him over to the police.
Sister Zero and Ivy's new job
Maggie Kyle reappears after the event of Blackest Night mentally unstable. She later finds herself in a home of a renown exorcist to save her. After thinking the exorcist is also in league with Selina's "cat demon", Maggie kills her and steals her exorcism equipment, discovering a container with a supernatural substance in the guise of an angel. This substance bestows her with supernatural strength and speed and a warped perception of reality and how she perceives reality, making it seem that she has an angel watching over her. She later sends Selina a message to come to the cemetery. When Selina and Harley arrive, she attacks the both of them. During the fight, Maggie somehow influence Harley Quinn making her attack Selina as well, but Selina manages to snap her out of it, forcing Maggie to escape and create a new plan to "save" her sister.
At the same time, Poison Ivy gets a job at the S.T.A.R labs in Gotham City. She is soon discovered by a former employee, Alisa Adams, who Ivy had fired on her first day. Adams tried to kill her in revenge, but was unsuccessful. Ivy, impressed by her cunning, decides to rehire her instead of killing her.
While working at S.T.A.R. Labs Ivy encounters an alien lifeform called The Alstairean and falls in love with him. Seemingly coming under the plant's control Ivy aids its escape from the lab, and makes Gotham Park where the entity plans on spreading his spores in an attempt to take over the planet for his Queen. Catwoman and Harley managed to make their way through the park to stop him, but they are stopped by the controlled Ivy. After Harley convinces Ivy that her relationship with Alstairean is like her and the Joker's, Ivy kills him with a kiss.
Selina is later kidnapped by an unknown party using her to find out the secret identity of Batman by trapping her in a dream sequence. Meanwhile, Ivy and Harley get help from both Talia al Ghul and Zatanna to locate her. They later find her underground with Shrike and the mastermind of Selina's abduction, Sempai. As the ladies fight for Selina, Selina manages to break out of her dream sequence without revealing Batman's identity.
Afterwards, Talia, despite the techniques used to help Selina being unable to reveal Batman's identity, decides to use Zatanna to wipe Selina's mind of Batman's identity. She kidnaps Selina, and Harley and Ivy goes to rescue Selina once again, but are prevented due to Talia's interference. Just when Zatanna is halfway finished with the mindwipe, she changes her mind and realizes why Talia wanted her to go through with it--because Talia was jealous that Batman showed feelings for Selina than Talia. Talia, furious, decides to launch a missile to destroy the building they're located. Zatanna manages to save both her life and Selina's but Talia escapes during the explosion.
Back at their hideout, Selina and Harley have a conversation about their love life. As Selina is describing her relationship with Batman to Harley, Harley begins to think about her relationship with the Joker. All of a sudden, Harley leaves and goes to an abandon Joker hideout for some items with Ivy and Selina following her. She then knock the two out with sleeping gas and goes to Arkham Asylum to kill the Joker.
Harley and the Joker
Harley later sneaks into Arkham Asylum on a mission to kill the Joker, using her wits. When she finally reaches the cell The Joker is located, she hesitates on shooting him, reminiscing the good (and bad) days with him. She then embraces him seemingly reconciling their relationship.
Meanwhile, Selina and Ivy later watches nearby Arklym Asylum waiting to make a move. When Selina hears an attack on Devil Square (due to Azrael) she leaves Ivy to deal with the situation causing strain between the two ladies.