George RR Martin has criticised the second season of House of the Dragon over changes to his plot that he says he “argued against” due to a butterfly effect, warning: “There are larger and more toxic butterflies to come.”

Martin, the author of the bestselling Game of Thrones books and the prequel Fire & Blood, on which House of the Dragon is based, has previously been very positive about the second season of the HBO drama, describing the first two episodes as “powerful, emotional, gut-wrenching, heart rending. Just the sort of thing I like.” However, last week, Martin wrote on his website’s blog that he would soon share “everything that’s gone wrong” on the adaptation.

In a post uploaded on Wednesday – which has since been deleted – titled Beware the Butterflies, Martin detailed his disagreement with showrunner Ryan Condal over the decision to remove one character, Prince Maelor, entirely from the show, which the author said will have future repercussions.

In the book, Maelor is one of the three children of Aegon and Helaena Targaryen, who also have toddler twins, Jaehaera and Jaehaerys. In the show, they only have the twins.

Martin said that Condal first told him in 2022 that they wanted to remove Maelor for “what seemed to be practical reasons … they did not want to deal with casting another child, especially a two-year old toddler. Kids that young will inevitably slow down production, and there would be budget implications. Budget was already an issue on House of the Dragon, it made sense to save money wherever we could.”

In the book, Helaena is forced by two thugs, nicknamed Blood and Cheese, to choose which of her children will be killed in front of her. She selects Maelor to die in order to spare the twins, but they ignore her choice and kill Jaehaerys instead.

In the first episode of the show’s second season, Blood and Cheese are tasked with murdering another member of the Targaryen family, but can’t find him so they kill Jaehaerys instead.

The author wrote that when he objected, Condal “assured me that we were not losing Prince Maelor, simply postponing him. Queen Helaena could still give birth to him in season three, presumably after getting with child late in season two. That made sense to me, so I withdrew my objections and acquiesced to the change.”

But, Martin said, he had since learned that “the prince’s birth was no longer just going to be pushed back to season three. He was never going to be born at all.”

Martin then laid out, in detail, major plot spoilers for how the absence of Maelor could affect the final two seasons of House of the Dragon, which will end with season four.

Of the change, Martin wrote: “It’s simplest, yes, and may make sense in terms of budgets and shooting schedules. But simpler is not better … Maelor by himself means little. He is a small child, does not have a line of dialogue, does nothing of consequence but die… but where and when and how, that does matter.”

He alluded to other disagreements behind the scenes, writing: “There are larger and more toxic butterflies to come, if House of the Dragon goes ahead with some of the changes being contemplated for seasons three and four …”

HBO issued a statement in response, defending the show’s creative team. “Commonly, when adapting a book for the screen, with its own format and limitations, the showrunner ultimately is required to make difficult choices about the characters and stories the audience will follow,” a spokesperson said. “We believe that Ryan Condal and his team have done an extraordinary job and the millions of fans the series has amassed over the first two seasons will continue to enjoy it.”

On a recent episode of the official House of the Dragon podcast, Condal said “everything is made available to [Martin]” during production.

“There are, of course, places where we have not agreed and departed,” he continued. “I’ve always tried to take aboard the notes. I’ve always tried to pivot and make the thing work. Does this help or does this help? Sometimes I think it works and connects and other points, it doesn’t. And I’ve accepted that. I’ve had to accept that as a condition of being a showrunner on a giant franchise.”