Vamp, Tramp, and Siren - SPOILER ALERT
It seems a lot of people see Nora as an innocent bystander in the story. I happen to see her in a different light. I believe people are responsible for their own actions but there are people who, for whatever reason, are a bad influence on others. It's as if they contaminate everyone with whom they come into contact. Nora Prentiss is one of those people. She is truly a vamp, a tramp, and a siren (like the sirens of legend who sing their song to lure men's ships into the rocks; leading to their eventual destruction and demise).
I believe her encounter with the doctor was hardly by chance; it was perfectly coordinated and orchestrated by Nora herself. Before meeting him, she did her homework. She learned everything there was to know about him right down to what would entice him to take an interest in her.
At first she may have been working with Phil. Singers at nightclubs like his seldom just sing. They're usually responsible for luring in customer who will be able to spend a lot of money. It may have been even more sinister than that. They may have set these people up so they could be blackmailed later.
When Richard treats her with kindness and respect she has a momentarily lapse and introduces him to Phil by another name. Instead of the doctor he's expecting, Phil thinks Thompson is just any other mark. Nora decides she might be able to move up in the world by landing a respectable doctor.
She puts on the charm. She plays into his weaknesses and does the good old push and pull routine to entrap him. Once the fish is on the hook, she turns up the pressure by playing the weak, helpless, crying woman who has fallen for him and is now in need of save. She pushes him away only to make him want her more. He has to play the hero and rescue the damsel in distress.
Everything is going great. He lavishes gifts on her, spends time with her, neglects everything else in his life. He can't see straight then suddenly he flips the switch, goes overboard, and ruins everything. She starts to lose interest when the lifestyle she craves is slipping away. Now he's become out of control and she's stuck in a web of her own creation. By the end of it she has driven him mad and has destroyed the man and everything around him. In her company he has fallen to her level. He must accept his fate.
Nora ends up having to settle for Dinardo; the man she never wanted. He has nothing she wants but she's come to realize she is who she is. She's not cut out for anything good. Naturally, Richard is not without blame. As I said we're all responsible for our own actions. However, like most men, he’s putty in her hands. He's easily tempted by a wanton woman and willingly succumbs to her charms.
Woman, man! That's the way it should be Tarzan. [Tarzan and his mate]