Can someone explain my sisters behaviour?

i disagree with jr, me and my sister are best friends. but before we became close, she used to be like this. we just fought so much that we became close through hard times. but for your situation, i think you should just say, look i love you obviously but if you dont want to ruin our relationship, then you need to start treating me like im your equal. tell her that just because your lives are different doesnt mean shes more special.