Adaptation Personality Change: Literally, as in 2 mermaids change personalities — The most distinguishing traits of Andersen's heroine were that she was thoughtful, quiet, and pensive (quite unlike Ariel), and one of her sisters is actually said to be by far the most daring and boldest of the family (quite like Ariel).

http://tvtropes.org/pmwiki/...ney/TheLittleMermaid
Народ постоянно забывает, что у Андерсена было шесть сестёр, а в мультике - семь.