First of all, I'd like to apologize for not replying to this thread anymore. For some reason, I wasn't notified of all the latest replies! That's weird.
Anyway, to reply to some of the questions in a more or less random order: I wrote the Succubus inspired by the "burned girl" archetype. She jumps from one dysfunctional relationship into another, as she believes that all of them are about utility - she has something people need (the Gifts), they have something she needs (souls). That's why she gives you strings because you did something without asking anything in return: you left her completely flabbergasted. Are acts of unselfish kindness really possible?
Essentially, the Succubus is all about discovering that not everyone is out to take advantage of you, and that you don't have to take advantage of them first by manipulating them into a position of weakness.