It should be noted that, though Mary may be as mentally developed as an adult, she retains an innocent, child-like personality. She demonstrates this trust when she calls for his help during the events that shortly lead to the ending A Painting's Demise. Even if she doesn't show it, however, Mary appears to possibly trust Garry at other points. Mary has a disliking toward Garry, since she envies his close relationship with Ib and wishes to use him as her replacement in the Fabricated World.

She especially seems to want to make lots of friends. During her time in the cursed gallery, she has read about a lot of things that pertain to the real world from books, such as the beach and candy, and wants more than anything to see these things. Mary's ultimate desire is to leave the Fabricated World and live as a human in the real world. In this state of mind, Mary would even consider killing (and make attempts to kill) Ib, who she wanted to be friends with the most, in order to increase the chances that she could finally fulfill her dream of becoming a human. When Garry does find out about Mary's secret, Mary becomes desperate to escape the cursed gallery before Garry could stop her. This sort of ignorant nature could have been a way of hiding her secret of being a painting and avoiding any deeper conversation about her rose so that Ib or Garry wouldn't notice anything suspicious about her. For example, when Garry first mentioned her rose, Mary ignored Garry's tips on keeping her rose safe, exclaiming how she liked Ib's rose color. While Mary's upbeat attitude may have been true to her nature, it may also have served as part of a ruse to keep Ib and Garry from becoming suspicious of her. Mary's behavior may be the sort of behavior her painter, Guertena, had imagined her to have. As the plot progresses, it becomes obvious that she has hidden motives. Mary appears to be a cheerful and innocent little girl at first glance, but she is also impatient and often misunderstands things. Yellow roses are depicted on the bottom of the canvas. Her canvas has a brown frame and is octagonal, with a smeary gray background. kouri, the artist and creator of the game Ib, drew her with the image of a 'lovely girl in a painting.'

She also wears black knee-high socks and green (sometimes brown) shoes that are similar to school shoes. She has a white collar and white cuffs at the end of her sleeves. She wears a green frock and a blue scarf, similar to the red ribbon that Ib wears. Mary is a young girl, with long wavy blonde hair, blue eyes, and pale skin.

Ib the game quote