Background
In this AU story, Edward is not the first of Carlisle's "children". Before him, Carlisle changed a young girl named Martha. After Carlisle changed Edward, he didn't take him home, but into a secluded area outside of the city (let's face it, I don't think Chicago has any forests around it like Forks does). Martha was worried sick for the three days Carlisle was gone, and this story takes place when he comes back with Edward.
Original Characters
Martha Cullen: Martha was born in 1791 in the still young United States of America. In 1806, at the age of 15, she was playing with a friend, and the friend's brother accidentally caused his dad's rifle to misfire, hitting Martha. She insisted she was fine, and attempted to walk home, not living too far away. The wound itself was not life threatening, but she lost a lot of blood, and ended up collapsing before she got home. Carlisle found her dying in the streets, rushed her to his home, and changed her.
When she woke up, Carlisle told her what she was, and she was terrified for a while. But Carlisle showed her his diet, and slowly over time she began to relax, and came to see Carlisle as her new father.
Carlisle and Martha have been together for 112 years with it being just the two of them.