The relationship between Charlie Harper and Alan Harper sometimes appears to not be to good. When they were children, Charlie would talk Alan into doing bad things for his own amusement, and so Alan that could get into trouble with their mother, Evelyn. When Charlie was killed, Alan was left heartbroken and lonely. For a while, Alan kept his grief bottled up until he snapped and went insane convincing himself that he was Charlie. He started dressing like him and behaving like the deceased. It is mildly implied that Alan was behaving this way to cope with the loss of Charlie.