This reminds me of Batman: White Knight. Joker is cured of his mental illness, returns home to Harley, apologizes and even proposes to her, wanting to start a healthier relationship. however, Harley instead attacks him and beats his ass while demanding he "puts on some make-up and go rob a back." the real Harley then shows up, beats up the fake, and takes Joker back to her apartment. The real Harley Quinn (Harleen Quinzel) fights the imposter Harley (Marian Drews) while telling the latter why she loves Joker; the original loves him despite his flaws while the new one loves him only for his flaws.
So... The best Harley is Harley.