Ooh, interesting world-building possibilities all around, from Ye Huo's history to the underground Dixing community and their relationship (or lack thereof) with the SID.
He's really the closest thing to a peer Lao Chu has, in a way--an ordinary Dixingren making his own way in Haixing, with basically good intentions, standing between the two worlds. I hope they get to be friends after the ending.