marilyn monroe, anna nicole. they just wanted to be liked, but all people wanted was sex. this made them feel like a blow up doll which led to drug use to tolerate their existence because they knew so much more. the drugs caused the chattiness, made it worse. both met the same end, sex symbold who truly just wanted to be accepted and liked for who they were, not expected to commit a sacred act of a sexual union. it gets to be too much.
chattiness comes from feeling uncomfortable, its from anxiety, carefree people tend to care the most; its a form of self mockery, or living up to a name put on you at a very fragile point in growing up.
I wouldn't write off the possibility that the chatty carefree girl is chatty and carefree :)
Interestingly, very few people ever suggest that the moping, morose girl is hiding the truth of her bubbly happiness :)
No. Maybe she's really care-free, or just clueless.