In the late 90s, Sally was a shapeless, smelly and sick old woman. She got dinner from the garbage and slept on benches and waited to die. She had given up on her life, and had nothing left to do with herself. Until she met Jesse Custer.
Custer came to McSorley's Old Ale House looking for information about a man named Cassidy, a man he'd thought was a friend. But he had learned many disturbing things about Cassidy and needed to find out more. So he went to one of the places he knew Cass loved.
The bar had changed, though. All the regulars were gone, and anybody who had known Cassidy had left. All of them except for Sally. Sally offered to tell Custer everything she knew about Cassidy, but warned him that knowing wasn't going to make him any happier.
Over a series of days, Sally told her story, and the story of Cassidy. She talked about how her friends were seduced and used up by Cassidy. She told Custer about the time Cassidy broke a girl's jaw, and about the time he tried to drink another one's blood.
She told him how she found the courage to tell him the truth - that he was an opportunistic, lying, bastard who thought he owned the world. That was the last she saw of him.
She told Jesse all of this, and then died on a park bench in New York City.