Her past isn't worth talking about it. Don't pressure her for information, as she won't give it to you. Fortunately over the years she's managed to learn that, while her past certainly has its effects on her, she refuses to dwell on it. Naturally that sort of thing still visits her in her most self-deprecating moments, but for the most part she has an almost forced optimistic attitude. "Only you can fix yourself." These are words she tells herself in the mirror every morning, and to some extent she believes them. Dependent is a horrible, useless thing to be in her eyes, so she refuses to allow herself to be that; she cannot allow those she cares about to define her.
As silly as it is, that's part of why she distances herself from others: a conscious effort to be as independent and in control as possible. She's well aware of the fact that she must seek comfort and happiness on her own. She's been somewhat successful at it, though she's aware it's a long road. However, the other reason she distances herself has a lot to do with how scared of others she is. When someone seems irritated with her, it's an automatic reaction for her to close her eyes and wait, as if she thinks something worse will happen.
She's terribly compassionate, though. A mere sob story will have her in a person's life forever, as she seems to be unable to practice caution. Not that she falls in love easily by any means-- in fact she's never experienced romantic feelings-- but she still doesn't know how to practice empathy with any measure of distance. As such, the distance she strives to achieve is outright ruined when she sees a person in a vulnerable state. There's no chance of her backing away in that instance.
She's also excessively polite, to the point of letting others tread all over her. Despite her forced hope, she truthfully doesn't think a lot of herself; she feels like she deserves a lot of the bad treatment she gets, so at the end of the day she's overly apologetic and worrisomely polite. She won't maintain eye contact for more than a few seconds at a time and is as jumpy and paranoid as they come; she's always looking over her shoulder, as if she expects a ghost to appear.
Marie's friendly enough, but only in passing. She grows uncomfortable easily in conversation and will flee at the first opportunity. It’s obvious that she feels uneasy at all times, despite the smile she may put on for others, and generally she’s careful with how she words things. Some interpret her to be a bit stupid, when in fact she’s incredibly sharp and quick to find solutions.
Underneath it all lies an incredibly creative and adventurous soul, however. Creation is her greatest passion (aside from helping others), and as such it's easy to find her painting, knitting, baking, taking pictures, or whatever else she finds to occupy herself with. Traveling is also close to her heart; she loves to see new places and learn new stories. When she's able to do these things, she's her true self: a quiet, but generally happy girl who is exhilarated by the simplest of things.