I had a foster son for a few months about 10 years ago. He was later diagnosed with personality disorder. He was 17 when he was with me. He could be very sweet and I liked him, but he had no conscience. He did drugs, broke house rules, and when we had to kick him out for breaking the rules, he went to a youth shelter. Broke the rules there too and got kicked out. Ended up in a terrible shelter for the homeless and decided to go back home. He came from a wonderful family who were at their wits' end. They made him leave their home because he was doing drugs, and they hoped that shipping him from Vancouver to Ontario would help him get away from bad friends. Anyway, the reason I mention this, is because of his complete lack of conscience and his ability to brilliantly manipulate those around him. It was quite frightening. And yet, he was so very likeable when he wanted to be. Very sad.