Doctor Harleen Quinzel, alias Harley Quinn, is a major antagonist in Kingdom Hearts Unlimited - Return of the Keyblade, first appearing as Quinzel in the second Gotham City campaign before having a larger role in her costumed identity as a member of the Suicide Squad in the Midway City campaign. A young psychologist working at Arkham Asylum, Quinzel was the first member of the staff to attempt to treat the Joker after his first defeat at the hands of Batman. The charismatic criminal managed to seduce the inexperienced and impressionable young Quinzel, convincing her to release him and join him as his partner, Harley Quinn. Despite their relationship turning abusive, Harley continues to be obsessed with pleasing her "Puddin'," even after being pressed into service as a member of the Suicide Squad.
"My name's Harleen. Harleen Quinzel."
"What a pretty name. Do your friends call you 'Harley?'"
"Oh, I don't have a lot of friends."
"Well, Harley, you got one now."
- The Joker first begins to charm Harley