I have come to the conclusion that the Sin Eater, the man who uses different names, is infact an aged Jeremy Crane.
1. The Sin Eater has special powers, so did Jeremy.
2. Jeremy did not have family. His mother and father ‘died’. The Sin Eater talks about how he has no family.
3. He does not like for people to touch him and he is private. This is obviously from centuries of being a loner.
4. Moloch wanted to kill baby Jeremy, not because he is just a douchebag, but because he knew that Jeremy could unconnect the first witness from the Horseman! D: