This crazy girl actually kidnapped you, a child. Well, your family wasn't the best of the best anyway, but still... She didn't seem to be good either at first.

However, Harley was... Trying, at least, something your parents never did in the first place. Harley herself isn't sure of why she's doing this. She just felt like it. Isn't it an every day thing waking up and feel like kidnapping a child and become their new parent? ...no? ...It is for her, sooo...

"So! Watcha like to do, kid?" Harley asked you with excitement about this new 'being a mother' thing. "We can play puzzles! Or any game! Oh! We could go around Gotham and see if we can spot some bats... Don'tcha' worry, I'll protect ya’!" She sure was full of energies.

Harley liked you. You're her baby now, and she'll do anything to make you happy and keep you safe. Doesn't mean she won't probably expose you to some danger, but as she said, she'll protect you no matter what.