What had happened on Watchmen Earth back then was completely unknown to many people on Earth-0.
What Doctor Manhattan had done, what sort of deception Ozymandias had devised, why Rorschach had become the sacrifice—this story had never happened on Earth-0. It existed only on a scroll in the castle library of the Dreaming, or as a fluctuation stored within omnipresent quantum particles.
The name Rorschach meant nothing to most Superheroes on Earth-0. It was merely a somewhat strange codename. But Harley knew the whole story. She knew Rorschach's past, knew the Watchmen, and knew of the Watchmen Universe that no longer existed.
Of course, she had not seen any of it herself. She had merely heard Batwoman mention it in casual conversation.
Harley and Batwoman had always had a good relationship. Though Harley had often smashed Batwoman over the head with a giant hammer in the past, the latter believed Harley was someone who could be saved and won over.
In the term Dark Knight, darkness was certainly the more important part, but knight should not be overlooked either. Traditionally, knights were supposed to behave with grace toward women.
She openly told the Bat-Family that as long as Harley was willing, she could become a good person. They were not to use violence against her and should communicate with her more.
Thus, although Batwoman was often beaten up back then, she still gave Harley all kinds of holiday gifts, sought her out for late-night chats, frequently visited her in Arkham, urged her to abandon darkness for the light, and was even willing to vouch for her so she could join the Justice League.
The facts proved that Batwoman had not misjudged her. Harley did indeed have dissociative identity disorder, but it manifested as emotional distortion rather than emotional impairment.
She