Pat and Sarah had long been friends, not just brother and sister. They supported each other, shared music and movies, and confided in each other as they went through the many challenging stages of adolescence. But something began to change in Pat. He was convinced people were watching him, spying on him. Once outgoing and sociable, he began to withdraw into a world of his own, on the inside, where social engagement was not necessary nor desired. He stopped taking care of his personal hygiene. Conversation became increasingly difficult. After a series of visits with psychologists, he was...