Gotham Knights has teased the inclusion of Harley Quinn, but it's unclear if she'll be on the side of the heroes or villains. Given the development of her character in recent years, it would be strange for her to be a villain in Gotham Knights. In addition, having Harley Quinn on the side of the heroes adds a fun dynamic for both sides.
Gotham Knights is an open-world game that takes place after Batman's death. Without the Dark Knight around to keep criminals in check, other vigilantes like Robin and Batgirl have to step up to protect the citizens of Gotham City. This game could set high expectations for future games in the world of Batman because Gotham Knights will feature the largest Gotham City yet.
The Joker is missing from Gotham Knights, but Harley Quinn has developed over the years into a character who is no longer dependent on him. Harley has spent enough time as a villain while she was obsessed with The Joker, and that role left qualities - such as her intelligence - overshadowed by her devotion to The Joker and doing what he wanted her to do. It would be a shame for all the development given to Harley Quinn over the years became meaningless by making her a villain again in Gotham Knights.
Harley Quinn Should Remain An Antihero In Gotham Knights
Harley Quinn has developed from sidekick to an antihero who is part of the Batman family. She would have been a better choice as a playable character than Batgirl in Gotham Knights given that she has a much more unique feeling to her character that would make her a distinct, fun choice. However, it's clear that she didn't make the cut for being a playable character, and might be made a villain once again for Gotham Knights. Harley Quinn doesn't need to be a playable character, but her being a wild card that helps the heroes out adds some much-needed variety to the Batman family.
Returning Harley Quinn to the side of the villains in Gotham Knights would undo all the development that has been put into making her character independent from The Joker's influence and finding her own place in the world. Denying the ways that Harley has grown into her own person over the last decade is insulting. The role of antihero is a perfect fit for Harley Quinn. It shows how far she's come from being controlled by The Joker, and her eccentricity would add levity to the serious group of heroes taking the lead in Gotham Knights.
