In my opinion, there are only two characters who Jane has battled to any degree all his life, himself and his arch enemy. These two opponents have remained central to every move he has made. Born into carny servitude for his father, his eventual emancipation and accention by marriage, his challenge and downfall and path of vengence. Personally I don't think his enemy has been a stranger Moriarty type character, or that I hope not because any character to oppose him must have more off everything that Jane has, to fulfill the arch enemy status. None of the suppose candidates so far have enough charisma to charm a goat let alone an army of martyrs. Beside his perpetual need to walk his path of vengeance, there is a central deep seated imbalance in his character which revolves around his father who made him what he is. I think his arch enemy should be Alex Jane, who has manipulated the master manipulator throughout his whole life including either becoming RJ, manipulating or enlisting him to bring the Boy Wonder full circle. Betrayal is paid with betrayal especially in tribal cultures like carnival folk. Alex Jane is his ultimate opponent and the most difficult to kill, all others he could execute with extreme prejudice including his colleagues and the one he has not calculated for. Personally any other character would be an anticlimax.