My theory is that the RPR avatar of Zenos is the fragment of Azem from the 13th that fell to Darkness. The reason Zenos was capable of possessing our body, despite Venat's Blessing supposedly being able to prevent that type of thing, isn't because of Zenos' Artificial Echo but because the Avatar is a Fragment of Azem and thus can freely join with our body. The reason that it was expelled was a combination of Fandianel's Tomfoolery and Zenos' own desire to fight us that he willingly left the body, taking the avatar with him since I doubt it would've been powerful enough to overtake Zenos as it was. Now that Zenos is "gone" that Avatar will now possess Zenos' Body, being the only thing that was actually a capable threat to us and will use it to traverse to other shards to forcibly rejoin the remaining fragments of Azem before trying to overtake us itself.

Maybe I'm totally off base but that's my theory at least.