OK my theory is that he's the human who betrayed the revolution at Oxford. I'm thinking he's been in with Nashira the whole time, and he's educated all his gang on the Rephaites and they're all working for them through their Mime Lord.
Inthink Jaxon is the human traitor from the bone season xxv111 rebellion. he has been building the syndicate for 20 years. That is how long it has been since the first rebellion. Plus, at the end Nashia said that Jaxon had returned to her meaning they had been together in the past....when he reported the rebellion (in which Arcturus was so badly tortured) and was rewarded with his freedom.
Wow, yes yes yes. Those are all good connections. Hmmm I may have to rethink my theory.
But that gives me more questions. Why did the Rag & Bone Man's minions all know about Rephaites and seem to be helping them?
Oooh true and good point... but then again, Jaxon didn't seem super surprised when he discovered the Rephaim. Alsooo, Jaxon and the gang broke into Scheol 1 - but how did they know how to get there and break in?
What do you think?