Leslie is a well educated and well mannered woman, who was originally a Vault City Citizen, but left when she fell in love with John (though that might've been the drugs he offered her). Their relationship was not a happy one, despite the fact that she gave him a daughter, Angela. Over the years, she grew to hate her husband along with New Reno. Seeking refuge in alcohol, drugs and the occasional sexual endeavor, she longs for a different way of life.
If the Chosen One is strong or attractive enough, when spoken to, Mrs. Bishop will ask him (or her) to accompany her to her chambers for a drink. Of course, this little meeting ends in bed. If the Chosen One doesn't have a condom in his inventory, he will impregnate Mrs. Bishop and trigger an ending for New Reno, where his son takes over the family and rules it until he dies in the age of eighty, never knowing his real father.
It should be noted that this is most likely canon, as in Fallout: New Vegas the singer Bruce Isaac states that he is being hunted by a "Mister" Bishop from New Reno, meaning that the Chosen One did most likely impregnate Mrs. Bishop. However, if the Chosen One kills Bishop sometime after and later convinces Leslie Anne to move on, his son will return with an army of tribals, taking over the city.
Regardless of sex, if the Chosen One performs, Mrs. Bishop will fall asleep contentedly and mutter the combination to her safe.
If the Chosen One has the Kama Sutra Master perk, Mrs. Bishop will have all dialogue options available.