The writers wanted Duke’s story about his mother to serve as sort of an “origin story.” His father gave him the Crocker Family Curse, but why did Duke become a smuggler and criminal? After five seasons, this story answers that question.
Audrey appears again. This time, she asks that Nathan leave her alone with Duke. Once that happens, she tries to convince Duke to take off her chains, making Duke suspicious. He decides Mara is pretending to be Audrey.