Enders Saga by Orson Scott Card. Not personally read the series but watch the Enders Game movie to see if you like the 'Universe' it makes, and if it catches your intrigue the give the Saga of books a go. Of course its the classic 'the book is way better' pinch of salt you need to take when you watch the movie (its alright... just alright, but in my mind the story has a lot of potential).