House of the Dragon is based on George R.R. Martin's book titled Fire & Blood, and, while the show has seemingly stayed pretty faithful to it, the Season 2 finale made a few fairly major changes to the source material.
Any page-to-screen adaptation will not stay completely faithful to the source material, but some are closer to their respective books than others.
However, when it comes to the Game of Thrones/House of the Dragon universe, both shows haven't made too many drastic changes, causing the main storyline to remain largely the same.
Every Major Change the House of the Dragon Season 2 Finale Made From the Book
Alicent's Journey to Dragonstone
The biggest change that House of the Dragon made from Fire & Blood since the show began in 2022 was the relationship between Rhaenyra Targaryen and Alicent Hightower. In the book, Rhaenyra and Alicent were never particularly close and were much further apart in age than in the show.
However, in House of the Dragon, it was always apparent that Alicent and Rhaenyra were as close as two people could get until they were forced apart by the war between their families.
House of the Dragon Season 2 already established that Rhaenyra wanted to end the war without bloodshed when it featured the Queen of the Seven Kingdoms traveling to King's Landing to meet with Alicent in secret.
For reference, that never happened in the book, so it will be no surprise when fans learn that Alicent never reciprocated Rhaenyra's actions and traveled to Dragonstone in the book either.
To further explain, Rhaenyra and Alicent never tried to secretly meet with one another and figure out a way to end the war once in the book, let alone two times.
That being said, Alicent obviously also never approached Rhaenyra and asked if she and Helaena could be spared from Rhaenyra's fury.
She also never told Rhaenyra of Aemond's plan to leave King's Landing for the Riverlands, essentially coming up with the idea of Rhaenyra taking the city and becoming queen.
Many events in the entire scene did not occur in the book. It is important to note that there is, however, technically no record of them not occurring either.
So, in a way, it is possible that it still happened that way in book canon, but it is highly, highly unlikely.
Jacaerys' Disdain for Rhaenyra's New Dragonriders
In the House of the Dragon Season 2 finale, Jacaerys was outspokenly upset about Rhaenyra's new dragonriders. He recognized them as bastards, and knowing that he was also a bastard, it seemed as though the fact they could ride dragons made him feel lesser.
In the book, Jace was the one to come up with the idea of bastards claiming the dragons on Dragonstone, not Rhaenyra and Mysaria, so he naturally wasn't upset when they were successful, but rather the opposite.
In the book, after Hugh, Addam, Ulf, and Nettles all claimed their respective dragons, Jace proudly led them in Rhaenyra's name. For example, one of the first major moments that occurred after the Sowing of the Seeds was the Battle of the Gullet, where he led the new dragonriders into battle.
Therefore, Jace's disdain for them in the show is slightly off-putting since he does not act that way toward them in the book whatsoever.
Rhaena and Sheepstealer
One of the biggest moments of the House of the Dragon Season 2 finale was Rhaena finally finding the dragon that had been roaming around the Vale burning and eating all of the sheep in sight.
This dragon's name is Sheepstealer, and is one of three wild dragons in Westeros, with the other two being Grey Ghost and the Cannibal.
In the book, Sheepstealer is not spotted flying riderless around the Vale after the Sowing of the Seeds, because, in the book, Sheepstealer is claimed right after the Sowing (although the dragon's claiming is technically still recognized as being part of the Sowing).
In the book, Rhaena takes no part in trying to claim Sheepstealer, and never goes on an escapade looking for a rogue dragon in the Vale. Instead, she simply accompanies Rhaenyra's children on the Gay Abandon and later claims her own dragon named Morning.
However, in the show, it seems as though Rhaena will (if she has not already) claim Sheepstealer and will be riding it when Season 3 begins.
In the book, Sheepstealer is claimed by a girl named Nettles, but Nettles doesn't even exist in the show, at least as of the end of Season 2, so she obviously cannot claim Sheepstealer.
Daemon's Vision
Daemon's character arc in House of the Dragon Season 2 was largely filled with visions/hallucinations while he stayed at Harrenhal.
In the book, Daemon was not plagued by visions whatsoever, and the source material even explicitly states that, when it came to Alys Rivers (who seemingly brought on his visions in the show), many believed Daemon was "immune" to her because it seemed as though her powers had absolutely no effect on him.
Therefore, it was likely extremely off-putting to some viewers to see Daemon struggle with being at Harrenhal so much.
Since he didn't have any visions in the book, he also didn't see any of the future either. So, seeing the White Walkers, Bloodraven, and Daenerys Targaryen were all things that Daemon never even knew or heard about, let alone saw.
Otto Hightower's Imprisonment and Ultimate Fate
Otto Hightower was featured on-screen in the Season 2 finale for the first time since the second episode of the season when he was fired from his Hand of the King position by Aegon II.
However, he was surprisingly not participating in some sort of cunning politicking but rather sitting in what appeared to be some sort of prison or dungeon cell.
It is unknown exactly where this cell is, meaning that no one knows where Otto was in the Season 2 finale, but it is clear that someone has him.
In the book, Otto was fired by Aegon the same way he was in the show. However, he was still in King's Landing after his firing when Rhaenyra and Daemon flew to the city, sacked it, and thus brought on the Fall of King's Landing, leading to Rhaenyra ascending the Iron Throne.
When this happened, Otto Hightower was made an example by Rhaenyra. Instead of showing mercy, she ordered him to be beheaded, and he was, although it was unclear who carried out the deed.
Seeing as how Aegon and Larys are leaving and Aemond will be flying out on Vhagar to meet Cole and march on the Riverlands any second, it is clear the Fall of King's Landing is close. It is possible that it could even happen in either the first or second episode of Season 3.
However, since Otto is currently locked in some sort of prison cell and is not at King's Landing, his fate in the show will play out entirely differently than it did in the show.
House of the Dragon is available to stream on Max.
More From House of the Dragon Finale:
Why Is Otto In Jail: What Happened to Him In House of the Dragon Season 2 Finale, Explained
What Happens to Rhaena & Sheepstealer? House of the Dragon Season 3 Spoilers from the Book Explained
Here's When House of the Dragon Season 3's Release Is Now Expected to Happen
Here’s Why Daemon Sees Daenerys and Her Dragons In the Finale of House of the Dragon Season 2
Aegon and Larys’ King’s Landing Escape Sets Up 1 Major Event For Season 3
