It was Marco in book #28.
The scene in #30 was "not to get all Prince of Egypt on you, but...behold!" that gave it away that he was human, but Edriss didn't put two and two together until he charged V3 to defend her, then blurted out "I love you" and tried to kill her, which was a pretty big giveaway. As for why Edriss suspected she might know him but couldn't put her finger on who he was, I always just imagine his voice sounds like his dad's.