Perhaps her most defining characteristic, Harley displays unexpected and erratic behavior. For example, throughout the movie, Harley sticks out her tongue at other suicide squad members or busts out an impromptu cartwheel. Her behavior, speech, and mannerisms appear somewhat childlike and playful. She makes jokes, laughs, and exhibits a sense of humor. Batman at one point describes Harley as “odd.”
As soon as she meets him, Harley begins flirting with Deadshot, who grows to become the “leader” of the squad. She does not show this same flirtatious behavior toward any of the other men (or women) in the squad. Despite his continued rejection, Harley eventually shows up naked in Deadshot’s bed.
As soon as Amanda Waller outlines the mission, Harley volunteers immediately to go into the suicide mission at Arkham Asylum. Laughing gleefully, she readily jumps into a fight. She appeared to enjoy freefalling in a crate dropped from a plane. She crashes, but responds to her team members, “Don’t worry! I landed on my head.” Near the end of the film, Harley undergoes electroshock therapy and enjoys it, calling out afterwards “I feel great!”
Based on these behaviors, Harley seems to have an affinity for pain. She does, however, seem to have natural fear of death and worries that Waller will follow through on her threat to blow any of their brains up.
Harley is also violent and explosive. Early in the movie, Harley bit off a woman’s ear in response to the woman taking away her cartoons. She also exhibits signs of impulsivity, for example, when she breaks from the mission and shoots at the Joker when he taunts her.
Obviously, as a comic villain, Harley also exhibits criminal behavior. In the movie, Harley never shows remorse for any of these violent or anti-social actions.
Anyone familiar with Harley knows about her on-and-off abusive relationship with the Joker. At the beginning of the movie, she refers to the Joker as a “jerk” and insists, “We’re through!” In tears, she actually blames Batman for her abuse: “You’re the one always hurting me…so I’m gonna hurt you!” Despite the abuse, Harley either plans an elaborate escape plan for the Joker or, upon his escape and perceived “win,” manipulates the Joker to take her back.