How to help friend's sister with realization of why people treat and discriminate against her?

It is horrible that so many people treat her the way they do. Honestly, you can't really protect her from these people. You could fight back, which may leave your friend's sister feeling even more "abnormal" and isolated because you are further drawing attention to her by taking the "bait" from the bullies. Also, this does not stop random people on the street or in the stores from stopping and staring. Unfortunately, you can't control everyone around her. I think what you need to do is to work on how she can improve her self-esteem and self-confidence. So many people think that self-esteem is directly related to physical attractiveness. However, it is merely a matter of being happy with who you are. What are her talents? What are her best features? Help her develop those. Feeling like we are good or "the best" at something helps us feel more important and confident. It doesn't have to be anything special, just something important to her. So, when people start staring at her, just lean over and say, "They're staring because they're jealous they don't have your eye color" or "Wow, that person was really mean and horrible. I guess they'll never meet someone as kind and giving as you if they treat everyone that way" or "That person is only mocking your speech because they don't have the vocabulary and verbal knowledge that you do" or "Try not to pay attention to the staring. You still make the best cakes in the state."