Byron Sully or "Sully" was born on a ship. He does not know the name of the ship or exactly where he was born; it was somewhere between England and America. His father was an English farmer before moving to New York with Sully's mother.
Sully's father died of heart failure, and his mother drowned in the Hudson River when he was only ten years old.
After the deaths of his parents, Sully moved west and ended up in Colorado Springs. Sully was once married to Loren's daughter, Abigail. Abigail died during childbirth along with the daughter she was carrying. Sully was heartbroken after the death, and he became somewhat of a loner, living in the wilderness with the Cheyenne.
He learned their ways and became skilled with a tomahawk. Due to his strong association with the Cheyenne, he became a liáson between the Native Americans and the American soldiers. It was Michaela who coaxed Sully out of his isolation.
Sully and Michaela became friends, and Sully finally allowed himself to face his fears and fall in love again. They were married and have a child together.