I'm trying to remember a book series I read in the mid-2000s. I've tried to remember as much as possible, some of the details might be incorrect. The book series is for young adults/teens and I think the author was Australian.
In the series, some people are born with superpowers and are recruited into the forces of the Babylonian god of Order (good guys), or the Babylonian god of Chaos (bad guys). The forces of Chaos typically travel back in time to alter an event (and thus make the present more chaotic), and the forces of Order have to travel back as well, identify the Chaos agents and stop them from changing history.
The two main characters were a boy (I think his superpowers include telekenisis) and girl at the same high school, in a town with a name similar to Angel Falls or Victoria Springs. Later on in the series a second boy is introduced who also attends the same school, but he is fighting for the bad guys. At the beginning of the first book the story centres on the boy and his mentor, a ~200 year old guy with purple eyes/hair (his superpower is not ageing). He operates from an ancient base underneath a large mountain.
Plot points include the main characters discovering their powers and learning how to use them, getting ingratieted into the order group and delving into the mountain in some sort of trial/ritual.
Can you identify this story?