From Catwoman #89, Harley has an idea for a TV show. Not surprisingly, it's based on a true story.
Good to know Harley's sexual fantasies are not just limited to men with clown faces and women with plant fetishes. She has room in that playfully wicked heart of hers for felines as well!
But hot lesbian sex between women in spandex isn't enough for the TV producers, so they demand an origin story. They demand to know the real Selina Kyle!
Breaking the fourth wall there, aren't you Harley?
And as a bonus feature to our proposed plot, Harley was already thinking of a Gotham City Sirens series, long before the idea got pitched to the men in DC's business office, but not before the launch of the Gotham Girls webtoon series.