Abigail had a sister who jumped overboard and Abigail misses her and mentions her in the story. Margot and Veronique were close and we see their relationship in more detail. Gaelle and Rose have a strong relationship. Only Winter ( as far as I can tell) does not have a sister as she was taken in by Mother Abigail as a baby. Winter is also a character who is more unsettled than the others. She is more of a misfit, not well accepted by the others in Remembrance and it often seems she is at war within herself. I wondered if this corresponded to her lack of another close, supportive, sister type figure. In each pair we are led to believe that one of the sisters has the power - while no mention is made of the other having any. I have wondered if this type of balance and closeness provided the acceptance and support that Winter lacked and thereby made her feel and behave as she did.