Riven

Two journeys. One inescapable outcome. No time to lose.
What should be a routine mission leaves Ethan with a serious problem. He's fractured—a break between mind and body that leaves him at the mercy of his Rifter abilities, which are quickly tearing him apart. He will have to trust the only person who might know how to fix him, a mysterious Rifter named Stewart Stills, who seems to have a special connection with the time stream.
Forced to face his dark past and a decision he may never forgive himself for, he will be trained unlike any of the others, to become a true guardian for time. If he accepts, it will mean leaving everyone he loves behind. If he refuses, time itself could unravel. After a glimpse of the dark future awaiting them all, he will have to choose between destiny and desire. Will he rise up and take his place as a defender of the natural order, or will he watch as all of time burns at the hands of the girl he loves?
Welcome to the time war.