The relationship between Rosalie Hale and Isabella "Bella" Swan is one that grows stronger throughout the series. Although, in the beginning, Rosalie showed a true hatred for Bella, later on, it became something completely unbreakable. It was all about understanding. Rose's story wasn't told until much later, and, one it was, the bond they had immediately grew stronger. When Bella became pregnant and then a vampire, Rose was always there for her. She protected her, kept her decently content (as content as you can be with a half vampire baby inside of you) and did everything she could to help the pregnancy go safely. When Bella was finally a vampire, Rose became something like an older sister, watching over her and protecting her and her baby. It's a lovely and amazing relationship and something that is rarely in a novel, especially one aimed at teenagers.