There are many comparisons and contrasts in The Witch of Blackbird Pond. Two more obvious contrasts are Mercy and Judith Wood. They have many things in common, but their personalities are very different.
Mercy and Judith are sisters. They are devoted to their mother. Both hope to marry someday. They both welcome Kit as part of their family.
Judith is confident and prideful. She is beautiful, and she is aware of this. Judith dislikes hard work, and she desires to marry a wealthy man. Judith is often unaware, such as when she thinks John Holbrook wants to marry her.
Mercy is content and humble. When she was very young, she became ill with a fever. She recovered, but her leg was damaged. She limps and uses crutches to walk. Mercy is content with her life despite her disability. She is fond of John Holbrook, but she does not object when he becomes engaged to Judith. She is kind and gentle to Kit. Mercy shows compassion to Kit upon her arrival:
Kit found Mercy's eyes and was steadied by the quiet sympathy she saw there (Chapter 3).