Wrong expression of feelings

I have known someone who wants to hurt the feeling of my niece. She is working outside the country and every time she calls my niece to say hi and she will always tease her in everything that she wants. Maybe she was happy doing it or just for fun. It is okay for me if she wants to fool around with my niece as long as the child will not cry to death of her teasing. Is this Normal? I guess this is the work of an evil. All I know is, children has the right to be happy in every way having a good memories in her formative years not that it will experience trauma or disrespectful and greedy to other person. My niece was so adorable and smart . At an early age of 6 she is already responsible and deals all the responsibility given and have the initiative to the needs of another person. She helps her mom in household chores, study her lesson without telling her, clean her toys after playing it and even her cabinet that is full of clothes was fully organized and detailed. How could such a person hurt her feelings even if she is a close kin to the family?. If this would make her happy and enjoyable for the moment, I strongly recommend to look for a help or a service of a psychiatrist. Or better look for a different way of happiness that could not hurt one's feeling.