For a good portion of the series, book readers were able to at least somewhat foresee what would happen to the characters of Westeros. They knew of Ned Stark’s beheading and the gruesome Red Wedding before they happen, all because these events had taken place in Martin’s novels. However, at the end of season 5, that all changed. The series has now extended far past its source material, making it impossible to know what will come next. Martin’s last book, A Dance with Dragons, was released back in 2011 and ended with Jon Snow's death. As of now, his sixth novel The Winds Of Winter has yet to receive an official release date, despite being announced in 2017. That’s a long time to wait for a new book installment to come out. It also means that the series could end up spoiling the books for fans instead of the other way around.