Harley is someone that doesn't require a huge amount of tweaking to make her work. So the only real change being that she's a student instead of a Doctor and that she like Barb will idealize a way of life rather than a person(joker)
Harleen Quinzel attends high school with Barbara in this retelling. She's Barb's mirror image. Rivals in gymnastics, she was the salutatorian to Barbara's valedictorian. But where Barb's focus was in law enforcement for her future, Harleen saw things otherwise.
During a college visit to determine where she'll attend after senior year, she snuck away from her tour group and tagged along with a group of Psychology students visiting Arkham Asylum. There she had her first glimpse of a personality that would shape her future.
She met a man who was clinically insane by all medical standards, but she saw him differently. She saw someone who was methodical, brilliant and only those who were fools couldn't see the social experiment he was conducting. He was showing them what true freedom was. Being second to no one because there was no structure to climb in his mind. He simply WAS.
Harleen had been bitter at always being ALMOST great in everything she did. ALMOST the best in school, sports and social climates. But what she took away from her stow away trip was a sense of freedom. A sense of self where she would no longer use society's rules for anything be it law, conformity or love. What she wanted she took, and what she wanted to do, she did.
Like Barb, she doesn't look at her symbolic icon (Joker) with an esteem or infatuation per se. More that she fell in love with his mentality. The idea of freedom he represented and from there she'll grow into her own villain using her own comparable skills to butt heads with Batgirl.