Moriarty had him set to the most meaningless tasks at first, things that he insisted that he just didn't have time to do, though mostly he just sat on his throne and ferried souls from there. He may have been an usurper, but he was actually doing the job.

When John was good, did what Moriarty wanted, he often ran his hand down Johns back or over his cheek or down his side, showing physical praise as well as giving him spoken praise, both of which increased as time went on.