Mary began as a sickly, ugly, spoilt brat who thought she could treat anyone the way she thinks they could be treated. She lacks affection from her parents and spends most of her days with her maid, Ayah.
However, when she moves to England, she slowly changed into a curious, energetic, and positive person. Her interaction with Colin, Ben, Red Robin, and Dickon made her believe in the power of magic which greatly improved her personality. As she spends more time, she becomes physically stronger and emotionally mature. She gains a sense of nurturing for the garden and Colin.