"........ She makes her life harder by being so contrarian to everything that is asked of her. It befuddles me because I'm the type of person who just does stuff when asked because it's easier than arguing or fighting about it. I like peace. She does not, apparently."
It's possible she is being contrary because her life is already hard. Or, what she perceives as hard. Also, her living circumstances are totally out of her control. Maybe she really would like peace, who knows? Has she had a very good taste of peace in her short life? Another thing to keep in mind is that she may be protesting simply because she doesn't like the fact that you have entered the picture and it's likely she perceives you as taking attention away from her Dad.