Following her introduction to the DC Universe in 1999, Harley Quinn was depicted as the sidekick and lover of the Joker as well as the criminal associate and best friend of fellow supervillain Poison Ivy. Later stories depicted Quinn as a supervillain who has left her abusive relationship with the Joker behind, beginning with the publication of her first ongoing series written by Karl Kesel in 2000. After years of scarce appearances in comics, Quinn returned in a leading role in 2009 with the Gotham City Sirens series, as part of an unstable alliance with Poison Ivy and Catwoman. In 2011, DC's line-wide reboot The New 52 reintroduced Quinn in the relaunched Suicide Squad title, which changed the character's personality, design, and origin, replacing her original jester costume with a revealing ensemble and depicting her to be darker than her earlier counterpart.