Their Comic Book Presence
The Joker is a character that is almost as old as his nemesis – Batman. He first appeared in the debut issue of Batman in 1940, and the two icons have been closely connected ever since. This means we were very familiar with the Clown Prince by the time Batman: The Animated Series introduced Harley Quinn to audiences in 1992. While The Joker is an integral part of the Batman canon, Harley was invented outside of that narrative, as a one-off supporting character in the animated show.
Audiences responded strongly to Harley, however – possibly because she enabled a different side of The Joker to be seen – and she became a recurring side-kick character in the show. She featured in the one-shot comic book, The Batman Adventures: Mad Love, in 1994 – but again, this was outside the Batman canon. Harley was not officially integrated into DC lore until 1999, with Batman: Harley Quinn, by Paul Dini and Yvel Guichet. This debut story finds Harley rejected by The Joker, which leads to her bonding with Poison Ivy. Ivy gives Harley strength, reflexes and immunity to poisons – something that proves useful in Harley’s ongoing, problematic relationship with the Clown Prince Of Crime.