Amber naturally has a rather sweet and shy demeanor, by the way she was raised and just according to her personality. This, of course, causes her to be target for most of the killers in the manor, who take advantage of her quite often, both physically and verbally. 

Since her personality is so stark against the rest of the vagrants and cold-hearted killers, she doesn't fit in, obviously, and the bullying normally causes her to hide in her room or out in the woods most of the time.