RE: A man blackmails a young woman he?ll inform the shelter and care program about her ongoing drug habit, leaving her homeless, unless she becomes his mistress.
I don’t think the stakes are high enough to keep her compliant on a long term basis. Plus, as his mistress she would have many opportunities to kill him.
In ‘Blue Velvet’, a deranged extortionist (Dennis Hopper) kidnaps a child in order to force the drug-addicted mother to become his mistress. Obviously, for the mother to submit she must be convinced this guy would have no qualms about killing a child.