The fact that she is so much fun to write has to be very similar to why actors/actresses love playing the villian/bad person... or perhaps I should just say "the severely flawed." They are so much broader! You can take them over the edge with much less self-consciousness or restrictions.

That could also be why POTC is so fascinating to explore: the writers provided each character with their own set of pluses, but also a quantity of flaws (well, very well, some more so than others ) So much to do, so little time!!!

BTW: Perhaps Caroline should look into this tendency to live vicariously through the looks exchanged between a man and a woman.