Harley Quinn: Mad Love: A DC Comics Novel
Paul Dini, Pat Cadigan

The definitive story of Harley Quinn by her co-creator, Paul Dini, and Pat Cadigan, revealing the secrets of her history even as she seeks to kill Batman. 

Dr. Harleen Quinzel grew up in an abusive household with a criminal and became a psychologist to deal with her own broken family. At Arkham Asylum, she attempted to treat the Joker and instead fell hopelessly in love with him, helping him escape and becoming a member of his organization.

Quinzel became Harley Quinn, a bizarre contradiction of violence and mercy. She blames Batman for her inability to maintain a stable relationship with the arch-villain, and that causes her to have an abiding hatred for the hero, who she seeks to kill.

Upon capture she becomes a violent inmate at Belle Reve Penitentiary, and is assigned to the group of government-maintained super villains known as the Suicide Squad.