Suicide Squad: 30 Easter Eggs & References You Must See
2. Between The Sheets
At the end of the film, just before the RIDICULOUS and needless jailbreak add-on, Harley Quinn can be seen sipping espresso and reading a book. That book, as eagle-eyed fans of trashy erotic romance will tell you is Between The Sheets by Molly O'Keefe.
It's raunchy trash, but importantly, it's where Harley gets her fantasy of "taming" the Joker from. The book follows a drifter bad boy called Wyatt Svenson who embarks on a strange relationship with his neighbour - a tight-ass who he thinks needs to loosen up.
The story of him basically leading her to her "wild side" and leaving behind her professional life (she's a teacher rather than a psychiatric doctor) is basically the exact model for Harley's transformation.