I agree that the curse brought out people’s worse traits and emphasised them but the traits had to be there to begin with. No way would Regina have had the time and patience to craft each individual personality in Storybrooke.
I think Ruby’s cursed state of being promiscuous has a lot to do with werewolves and their links to women’s menstrual cycles aka that time of the month. Ruby turns into a werewolf because she’s young and in her prime whereas Granny doesn’t because she’s old and post menopausal. Because Ruby couldn’t turn into a wolf during the curse, it is likely “the wolf” had an influence on her behaviour. For example, she was on the “hunt” for men.
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All magic comes with a price!
Keeper of Felix