Fractured Worlds Trilogy Series by Alan VanMeter

When Leena and Tristan won the contest of a life time, they had no idea that this would quickly become struggle for life itself. Finding themselves on a strange new world in the blink of an eye, even far removed from their own galaxy; they found they had to grow up in an awful hurry, or die. It wasn't their fault they became entangled in the culmination of a quite ancient intergalactic conflict, but it would be their doing which would end such. This was also the end of their innocence however.