Christine

What happened to Christine?
From earlier episodes in the Aeolus Investigations series, we know that she is the daughter of Lexi Stevens. We know that as an eight-year-old she had proved herself "weirdly" awesome. There is evidence that she somehow managed to make her way 6,000 years into the past. It's pretty conclusive evidence -- Allie Stevens recovered a 6,000 year old porcelain tile with a message addressed to her from Christine the summer Allie worked at an archaeological dig in Peru. It was a short message, telling her that she should trust the stranger she had fought with -- a man named Quetz.
On top of that, a 6,000 year old stone block had been recovered from the bottom of the ocean. The message carved into it was to Lexi, also from Christine.
Since both messages where discovered before Christine had been born, the adults had their memories of them blocked. When the time was right, Urania, a computer sentience whose thoughts couldn't be telepathically picked up by Lexi's precocious daughter, would release the blocks. Lexi didn't want Christine to know she was likely to wind up in the past before it happened.
Travel with Christine and her hurriedly assembled team back in time, before the Mayans and the Olmecs, to the ancient X'huatan civilization whose goal is the conquer Earth and to prevent Lexi Stevens from ever having the opportunity to become the Marshal of the Accord. The X'huatan hadn't factored Christine into their plans.