Talbot Hall/Boarding HouseEdit
Prior to the story, Harley knew Peter from childhood and unknown to him, has had a crush on him since then. She does care for Peter, a great deal because even when she was infatuated with the Joker, he was always on her mind, but pushed the crush aside in order to avoid hurting him.
But after her realization of the Joker’s true nature, and meeting Peter again after ten years, or the fact that he turned her into a werewolf to save her life, her crush rose again, though she never expressed her feelings until after she found out about her replacement and her ‘predecessors’.
As time went on, she later started to fall in love with him more and her love became deeper after he saved her from one of Black Mask’s obsessive assassins: Talon of the Court of Owls, who was hoping to lure Alpha to kill him, and for recognizing her as Harley rather than the Joker’s girl or a criminal from Arkham. She and Peter both shared their first kiss in a long time with each other after her rescue.
She often gets jealous when other girls flirt with or tempt him, even saying that Peter belongs only to her. She loves him very much and is willing to do anything with him. In response, Peter will do anything to protect her, as he loves her just as much as she loves him (unlike the Joker who just beats her up).
To add to that, she usually sleeps next to Peter naked. For this reason, she says that she has no problem with letting Peter see her naked and they even make love from time to time.
She and Peter had met Mikey in middle school, mostly due to a tutoring agreement. However, the two boys had bonded to be friends after spending time together and sharing interests, even Harley thought it was a hoot to have Mikey around, seeing him like a big brother figure.
Though Harley is a bit wary of Mikey's little hobby of filming girls in bikinis, underwear, or even in the nude. Something of which Harley analyzes that he is in desperate need of a girlfriend. That way, he can just film and photograph her than every girl that he seems to spy on... which she's still amazed to wonder how he can do such photos
Like Peter, Harley trusts him enough to be the eyes and ears alongside Humpty.
Harley has always seen her as a precious little sister. Something she has never had when growing up in a family of brothers. The two are on very good terms; both friends since a young age.
Daphne Isley is actually a plant clone of Poison Ivy that she had created to keep Batman busy, but to keep Harley company for a friend. Unlike the other clones, she is actually Ivy's 'daughter', since she was uniquely created. Harley has an on-again, off-again friendship/partnership with her, with whom she works well. Ivy has always had a soft-spot for Harley, often stating that that Harley had no need for Joker. However, Harley never seemed to accept that Ivy was right, until the Mad Love incident.
This along, with her flaky personality would often cause Ivy great annoyance, but never to the point that she would sever ties with Harley.
Though Harley was more than surprised to learn the truth from the real Pamela Isley, after they found out where she was after an unstable Ivy was coming after her to 'save' her from Peter, that the Ivy Harley was with was actually an advanced human/plant hybrid. Asking Harley if she felt any different... Harley shook her head, saying she's just as much as Red as ever.
After she and Peter turned her with a special chemical restorer from Pamela to help stabilize and save her, the two once again started their friendship as teammates, with Poison Ivy renaming herself with a new identity, Daphne Isley (posing as Pamela’s long lost twin sister), calling each other by their nicknames of Red and Harl. She is very close with Harley, displaying a big/little sister relationship in public while maintaining their friendship as well, but now she is one of her strongest rivals for Peter's love since she became her rival, when Peter saved her, and she fell in love with him.
Ivy and Harley are bitterly fighting each other over Peter's love and she is considered her biggest rival: something that Peter is in the crossfires of. Despite this, the two of them still care greatly for one another.
The two seem to have a good friendship so far, as Harley loves Roxy's adventurous stunt life. She even urges for Roxy to be the one to drive/fly/operate any vehicle they are thrown into.