I'm starting to wonder if there's something fundamentally special about our/Azem's soul in particular after recalling how Hythlodaeus mentions that the Ancients trapped within Zodiark lacked clarity of mind specifically until we arrived on the moon, then Hydaelyn/Venat later mentions that we have a curious quality of attracting souls to us.

It could have something to do with our particular manifestation of the Echo, but it wouldn't surprise me if we ended up having some deeper connection to the Lifestream or Etheriys itself; especially given how there seemed to be some bigger problem at hand only Azem was aware of.

By extension, if Zenos' avatar really does end up being our 13th shard and a problem that needs to be dealt with in the 6.x series, rejoining with it might end up kindling an awareness of that something that could play into 7.0's plot.