Who is Duane Harvey from The Winner and what is their importance?

Duane Harvey is LuAnn's boyfriend and Lisa's father. LuAnn and Duane live together, but she has no hopes for marriage. Duane is not well educated, and he appears to be unemployed, as he spends the majority of his time in a drunken stupor. When LuAnn decides to leave Duane, she strips the sheets off of the bed and accidently uncovers Duane's hiding spot. There is a tremendous amount of money under the sheets, and LuAnn has no idea how he came to possess it. Soon after, a man appears at the house and kills Duane and injures LuAnn. LuAnn correctly assumes that Duane was involved in drug dealing.