HBO’s Game of Thrones has cultivated the impression that Season 5 will prove the most divergent yet from series creator George R.R. Martin’s literary works, yet the man himself can still be surprised. The Game of Thrones author recently teased that Season 5 will feature multiple character deaths not found in his novels, calling the showrunners “even bloodier than I am.”

Speaking with Showbiz411 at the Writers Guild West Awards, Martin warned fans against relying on their knowledge of the books, as showrunners Dan Weiss and David Benioff will kill off characters still-living through Martin’s work on book six, The Winds of Winter:

People are going to die who don’t die in the books, so even the book readers will be unhappy. So everybody better be on their toes. David and D.B. are even bloodier than I am.

Of course, HBO’s Game of Thrones has already taken quite a few liberties with the source material, combining and re-imagining characters to condense storylines. Season 2 characters Irri (Amrita Acharia) and Xaro Xhoan Daxos (Nonso Anozie) both remain alive in Martin’s books, while Season 4 finale “The Children” (spoilers!) killed off Jojen Reed (Thomas Brodie-Sangster), despite the character enduring in the text.

Martin also spoke to the potential longevity of the HBO series, which for the moment has been envisioned as seven seasons:

Not really certain yet. This is the fifth season, the sixth season HBO picked up last year. We will have a 7th, 8th or 9th, no one knows. They only renew one or two seasons at a time. After we do season 6, maybe we’ll get a renewal for 7th and 8th. That all depends, Television is a very changeable medium. […]

Whatever happens with the show I’m going to finish the books, it will be seven books. But each of these books are 1500 pages long and they each have enough material in them for several seasons. I have two more books, the one I’m writing right now, ‘The Winds Of Winter,’ and after that the last book, ‘The Dream of Spring,’ so those will be the two final books. But we’re talking 3000 pages of material. How many seasons that translates too [sic]? That’s up to D.B. And David.

Elsewhere of Game of Thrones Season 5 (already renewed for 6, with the cast signed through 7), we know of multiple returning, confirmed absent, and new characters cast, including those that confirm we’ll be visiting the oft-mentioned kingdom of Dorne, for which Spain doubles. The story will draw heavily from George R.R. Martin’s fourth and fifth novels, A Feast for Crows and A Dance with Dragons, while HBO has also provided a list of directors, as well as insight into which literary stories may not make the transition to film.

While we wait, there are still plenty of Game of Thrones Season 5 photos to pore over, as well as the full trailer below (and our beat-by-beat breakdown), and even the full “Day in the Life” special as we count down to the April 12 premiere!