I'm honestly thinking that mystery person in white is Unukalhai, from the Warring Triad quests. He's a WOL from the 13th, trained by Elidibus himself. On his first meeting, Zenos remarks about his soul, as though there is something unique about it...If he's another WOL, he might look similar to Zenos' favorite 'friend'. The speech pattern is not the same as Asahi's....different rhythm and pitch, even if the same VA. He calls himself a dog, looking for a new master...Another hint, I think. Unulkalhai also keeps referring to Elidibus as his master, throughout the whole questline. I can even think of an altrusitic reason for him to want to sic Zenos on Zodiark...He's realized that his master is tempered, and the only possibility for getting him free, is to kill zodiark.