Miss Dolly lived until the age of 9 with a sister one year older than her. They were close enough that whatever Molly did, Dolly did. Dolly was prepared to fight for Molly, lie for her, or anything else that Molly might have required. There was no such thing as 'too far' for Molly. In her defence, Dolly claims that what she did, she did in defence of her sister. Dolly tells the group that her sister had grown sick and died, right before Dolly came to the school, but that the habit of standing up for her friends was still with her. This is why she entered into the quarrel over the apple.