Ahem, I didn't pay much attention to the DC universe. Or Marvel for that matter.
Maybe this will explain Harley Quinn's personality:
My sister told me, in one of the old comics, Harley was fighting with Black Canary (I think?) and at the time BC was pregnant, and she nearly fainted in the middle of the fight because of sickness. Harley stopped the fight, and sat down next to her to help her sit up. BC was like, "Wat." And Harley was like, "I'm not fighting you when your pregnant! Maybe later?" Yeah.