Hep was an unusually tall and large framed woman. She lived in a rundown shack with her brother, aiding him with criminal activities.
Marty McFly first encountered her in 1875 while on a mission to prevent Thaddeus from stealing the ranch of his girlfriend Jennifer Parker's family. Hep immediately formed an attraction to Marty and as a result, Thaddeus made Marty a member of his gang and gave him the blessing to marry his sister.
After Marty escaped out of the forced relationship, Thaddeus's fellow outlaw Ox McPhips revealed that he had been in love with Hep all along. Hep turned Thaddeus over the police and left a life of crime to live with Ox for the rest of their lives. Ox and Hep were married and opened an ice cream shop.