The following words are meant to support the above statement. (Please note that all following is based on the manga story.)
Oscar was an idealist, maybe it was that what made her life so difficult. Realising how many people lived on the edge of prosperity when she had more than she needed, and above all knowing that the queen did not realise their misery, and her reaction to all this, shows what she wanted the world to be like. And she was an idealist thinking it could ever be like that. Though I still think it is a cause worth believing in.
She was also a brave and dedicated soldier, knowing her duty and she was skilled like hardly any other in Versailles. She would give her life protecting the queen or someone else that meant a lot to her, like Rosalie or André.
But nevertheless, she always remained a woman, a passionate and caring woman, who often suffered from the burden that she had to carry. She was also a very impulsive young woman, who often failed to hide her feelings, except for that one feeling which she hid so perfectly, that not even she herself knew about it. It was the love for her companion, André, a love that merely had short time to bloom, but will never die.