I need some help figuring out this girl's personality?

There's this really quiet girl in my school i'd like to be friends with. She doesn't seem to have any friends and i've been in most classes with her since Elementary School. (See my other question) So apparently shes protected quite a few kids in this school from bullying and from getting hurt. Ive seen her crying quietly in class a few times and I see her eating french fries a lot at lunch at the small table she always sits at by herself. Theres this German Shepherd I see walking with her to and back from school everyday to, I never see her parents. Shes never spoken a word as far as i'm concerned and I always see her seem to get nervous in crowds of people. When people make her mad she bites hard enough to make you bleed which is how she got the nickname 'Lone Wolf'. Sometimes she comes to school in weird things like PJ's and baggy shirts. She also sleeps a lot in class to and the teachers dont seem to care. I think she also likes sweets to. Can you tell me what you think her personality is like?