The flow of time and history isn't as straight as people think. Every choice ripples out and causes the timeline to branch off into several more lines, each headed for a different future. However they are connected all the same and should one head into completely destruction then the rest will follow.
And that's why an all-seeing deity had chosen ten individuals from other realities and timelines. Together they are the best chance to tip the scales in order to save all of reality. But whether they succeed or not is really up to them.
Note: Inspired by Powerdrainer's "Guilt of a Phantom" and written with permission from said author, a great read and I highly recommend it if your a fan of Danny Phantom.
Starts before the start of GoaP.