Doll is a young female who is affiliated with the Noah's Ark Circus. When she was still under her parents care her left eye was badly burned and marred due to their ruff handling and abuse. She hides this with her well placed side fringe.
When she performs or acts as the first string member of the Noah's Ark Circus, she is solemn and taciturn in expression and manner. However when she adopts the persona of Freckles, Doll is cordial, welcoming, and somehow innocent, easily befriend others, such as the trap Ciel Phantomhive. 'Freckles' is shown to be very kind to Ciel, taking him under her wing and making sure he wakes up on time, shares her food with him when he doesn't get enough and teaching him how to perform.
Doll is not modest, as shown when she attempted to get Ciel to take a bath and offered to wash his back for him. She even allowed him to touch her chest — in fact, she had unflinchingly laid his hand there—to prove that she is female, and gave him permission to "take a peek downstairs." This is most likely because of her life in the streets before she was taken in by her 'Father' Kelvin. She is very family orientatded orientated, as shown by her love and loyalty to her adoptive street family, Joker, Beast, Dagger, Wendy, Peter and Jumber. This later extends to her 'father' Kelvin, the children at the orphanage, members of the circus, Snake and Ciel or 'Smile'.
Reason For Cross-Dressing
It is believed that Doll doesn't purposely cross-dress when wearing her casual attire, unlike the other first string members who seem to always wear their costumes. It is likely that she wears this because it's more comfortable then her stage costume, although another factor is because she didn't immediately want Ciel to know that she was Doll, as she cannot sleep when no-one else is in the room with her. (this is believed to be because of her abusive parents), and doesn't want him to refuse to sleep in the same tent as her.