I need help and I don't know what to do. I have an 18 year old nephew who I feel has a severe mental problem that I can't put my finger on. His parents are divorced and he has not spoken to his father due to verbal abuse from him since 2009. He is extremely intellegent (IQ of 152), but I feel he is just filled with anger that he does not know how to release. I just bought him home a puppy on Sat and he is fixated on the puppy. He named him some name that I could not even pronounce and I kindly said, "Well, maybe we can give him a nickname that is easier to say". He replied, "If you call MY dog anything other than what I named him, I will stab you and that is not a threat, it is promise. He later told me I could not take pictures of the puppy and called his mom and said, "If you don't take care of your sister, then I will have to and I will have to take it to the next level". She asked him to explain and he said, "I will raise by voice at her and if that doesn't work, I will have to take it to the next level". She responded, "What does that mean?" He replied, "I would have to pin her up against the wall!" I am so upset and I don't want him to have the puppy, but fear he will cause bodily harm to my sister or his brother who he absolutely despises. Can you offer any suggestions? Thank you.