In her early years, Leslie was a close friend of Thomas Wayne's and immediately took it upon herself to look after Bruce when his parents were killed. During this time, Leslie became concerned with Bruce's behaviour as he became anti-social. She was even more disturbed when she discovered that, in his later years, Bruce spent his nights dealing with the criminal elements as Batman.

Leslie disapproves of his methods due to her belief that violence doesn't solve problems, but at the same time wonders if her lack of time with him during his childhood may have lead to his current state.

In a move that has shattered her friendship with Batman, Leslie deliberately let Stephanie Brown die when she was wounded by Black Mask. Leslie was shaken by Stephanie's injuries and made this decision to show Batman the consequences of his war on crime. Leslie has since left the US and works for relief agencies abroad.