Malefactor, later referred to as Moriarty, is the main villain of the The Boy Sherlock Holmes series. He originally helped Sherlock, but soon attempted many times to get him killed. It is assumed he is based on James Moriarty.
Little is known about his early life. All that is known is that he was born in Ireland and was wealthy, but his parents decided to move to England. When he was 8 years old he lost his family - his father, mother, and younger sister. Eventually he formed a gang and became a powerful leader.