KW said into an interview 'I don’t want to give too much away, but we’re in addition to following the books to some degree, we keep going back to the books and saying, “What can we pillage? What have we not done yet? What have we not used? How can we take this storyline and manipulate it and change it and turn it around?” This year, we’re diving into the Original family, we’re still playing with the hybrids and so the whole thing with Klaus is going to lead us right up to the climax of the season.'.Here's the link : link
They use parts of the books. What do you think they will use next? What did they already use?