Even before the show had even started, House of the Dragon deviated from the source material in some significant ways. The events surrounding the monumental civil war waged by House Targaryen, known as the Dance of the Dragons, will be depicted in the prequel series, which begins roughly 200 years before the timeline of Game of Thrones. When King Viserys I Targaryen dies, his children’s loyalties will be divided: the “greens” will support Viserys’ eldest son Aegon II Targaryen’s claim to the throne, while the “blacks” will support Rhaenyra Targaryen’s declaration that she is the rightful heir.

George R.R. Martin’s book Fire & Blood inspired George R.R. Martin’s HBO series House of the Dragon, which chronicles the rise and fall of the Targaryen dynasty in Westeros. A major benefit of House of the Dragon’s adaptation of Fire & Blood is that it is more informational than the narrative-driven Game of Thrones. There is no definitive confirmation in the book that the sources can be trusted to be completely accurate, leaving many of the book’s most dramatic plot points open to rumor and interpretation.

However, the narrative details and twists in the Game of Thrones books are extremely important to the character arcs and should be taken literally. Herein lies the problem that Game of Thrones on HBO has caused for readers of Martin’s A Song of Ice and Fire, which the show has surpassed by the fourth season.

Given the less tangible nature of Fire & Blood’s history, House of the Dragon’s alterations won’t be as dramatic as those in Game of Thrones, but the series’ decision on which side of the speculations to make fact will still have major repercussions.

The trailers and announcements for House of the Dragon by HBO have already hinted at significant changes to the book before it has even premiered. All sorts of things start to change in the first few books of the House of the Dragon series, from characters’ outward appearances to how long they manage to stay alive.

More Targaryen Traits In Rhaenys Targaryen Than In Baratheon

The Queen Who Never Was, Rhaenys Targaryen, will be a pivotal figure in House of the Dragon. Her father, Aemon, was King Jaehaerys I’s eldest son, making her the rightful heir to the throne. However, because of her gender, she was disinherited. Instead, her son Laenor Velaryon and King Jaeharys’ eldest grandson Viserys Targaryen faced off in a Great Council vote in 101 AC, with Viserys Targaryen emerging victorious. In the Dance of the Dragons, Rhaenys Targaryen’s ardent support for her cousin Rhaenyra Targaryen’s claim to the Iron Throne will be crucial.

However, Rhaenys’ character is altered significantly from the novel in House of the Dragon, and these alterations may have a significant bearing on why she was not chosen as heir. Rhaenys Targaryen, who was born to Jocelyn Baratheon, is said to have inherited her family’s signature jet black hair. The silver hair of the Targaryens is a distinguishing feature of the House of the Dragon, so the fact that Rhaenys possesses it may have swayed the council in her favor as an argument for her selection as heir.

Even though she was never called “Rhaenys Velaryon” in the book itself, that is the name that appears in the book’s promotional materials. An important plot point could emerge from Rhaenys’s perceived allegiance to the Velaryons rather than the Targaryens and the council’s desire to see a ruler adopt the surname of the Targaryen family tree.

House Velaryon Doesn’t Share the Targaryens’ Pasty Whiteness

The visual appearance of House Velaryon has also been altered from the novel House of the Dragon. The Velaryons of George R.R. Martin’s books has the same Valyrian blood and physical traits as House Targaryen, including fair skin, silver hair, and purple eyes. House Velaryon in House of the Dragon has dark skin and the silver hair described. The Velaryons, however, are still likely to have Valyrian blood, which will make them adept Dragonriders, so this is not a huge change.

Rhaenyra Targaryen, heir to the Iron Throne, and her sister Laenor Velaryon have been rumored to have had three sons with her sworn shield Harwin Strong, which this book revision may confirm.

It was widely believed that Laenor was gay in Fire & Blood, and when combined with the fact that neither of their sons resembled either Laenor or Rhaenyra, it became widely accepted that Harwin was their biological father. Their son Jacaerys Targaryen is played by Harry Collett, who is cast as a pale man with black hair, suggesting that the children are Strongs rather than Velaryons.

King Viserys Is More of a Downer

George R.R. Martin hinted at an upbeat alteration to the book version of House of the Dragon when he said that the HBO adaptation of King Viserys I Targaryen is an improvement on his own.

By revealing that Viserys in House of the Dragon possesses a “tragic majesty” that Martin’s character never did, Martin has likely increased audience investment in Viserys before his death. Since Viserys’ death is the catalyst for the Dance of the Dragons, it makes sense to give him more attention and development earlier in the series than he received in the book.

A Change Was Made To Ser Harrold Westerling’s Death

Ser Harrold Westerling’s age was one of the first book-to-movie discrepancies noticed after the release of House of the Dragon trailers. As the book’s timeline goes, Harrold, the Lord Commander of the Kingsguard, passed away in 112 AC due to old age. This was only a few years into King Viserys Targaryen’s reign. In Fire & Blood, the character didn’t play a major role, but in House of the Dragon, that appears to have changed.

Harrold Westerling, played by The Hobbit’s Graham McTavish, would have died two years before the wedding of young Rhaenyra Targaryen and Laenor Velaryon, but the trailer places him in events from the House of the Dragon that take place after the time jump and adult actor changes. Since Harrold is still alive when Laenor dies in 120 AC, he will likely play a significant role throughout the series. When Harrold passes away, Criston Cole will take over as Lord Commander of the Kingsguard.

Alterations to the Bond Between Corlys and Vaemond Velaryon

House of the Dragon also deviates from the source material by making Corlys and Vaemond Velaryon relate to each other rather than being friends. Although Vaemond is Corlys’ younger brother in House of the Dragon, he is Corlys’ nephew in the book, putting him at a remove from the struggle for the throne of Driftmark.

Driftmark will pass to Laenor’s three sons with Rhaenyra and Laena’s two daughters with Deamon Targaryen upon their deaths in House of the Dragon. Vaemond, Corlys’s brother and the “legitimate” male heir to Driftmark, stands to gain prominence as he campaigns for the throne.

Alicent Hightower wields a dagger made of Valyrian steel

Alicent Hightower, as an adult, lunges at her stepdaughter Rhaenyra Targaryen while brandishing a Valyrian steel dagger in one of the most shocking scenes shown in the trailer for House of the Dragon. This is a valuable Valryian weapon, and it appears to be the same catspaw dagger used in the attempted assassination of Bran Stark in the TV series.

Alicent’s physical assault on Rhaenyra with a Valyrian steel dagger was never depicted in Fire & Blood. The trailers for House of the Dragon have given extensive screen time to the dagger, implying that it will play a role in the film beyond the scene with Alicent and Rhaenyra. After Alicent’s son Aemond loses an eye in a fight with Rhaenyra’s son Lucerys, it’s speculated that she lashes out at Rhaenyra in rage, demanding in vain that Lucerys also lose an eye in retaliation.

The Iron Throne Is Noticeably More Diminutive

A major complaint about the HBO series was how the Iron Throne was portrayed, although the show diverged significantly from the George R.R. Martin novels. Many who dared sit on the Iron Throne were subsequently harmed by its haphazardly placed swords, which were described as standing 40 feet tall in the books. The Iron Throne in “Game of Thrones” was nothing like this; instead, it was a much smaller and less ominous structure.

The Iron Throne in the books is depicted more accurately in House of the Dragon than in Game of Thrones, but the television show can’t compare to the books in terms of the throne’s imposing stature and terrifying power. Instead, more melted swords are placed on the stairs leading up to the seat in House of the Dragon’s Iron Throne, implying that future kings or leaders had removed them before the events of Game of Thrones.

The Estate of House Tarly

In the trailer for House of the Dragon, we see our protagonists competing in a massive tournament at Horn Hill, the home of House Tarly. But the Targaryens never showed up at any such event in Fire & Blood, so either this tourney is made up for House of the Dragon, or the location of tourneys in the show has been altered from what they were in the books.

King’s Landing hosted the Tourney of 111 AC in honor of Viserys and Alicent Hightower’s fifth wedding anniversary, while Maidenpool was the site of the Tourney of 104 AC in honor of Viserys’ ascension. Horn Hill may have been substituted for Maidenpool in this later event.