'House of the Dragon' just made a major change not in the book. It could make the Targaryen family tree even more complicated.

The latest episode of "House of the Dragon" includes a major change to the Targaryen family tree not featured in "Fire and Blood." Here's why it's an important change.

• Hugh Hammer claims to be related to some popular Targaryens in the latest "House of the Dragon" episode.
• In "Fire and Blood," he is also a bastard, but his parents are never revealed.
• Here's how this could change the storyline for future seasons of "House of the Dragon."

Warning: Spoilers ahead for "House of the Dragon" season two, episode seven, and the "Fire and Blood" novel.

Hugh Hammer casually drops a massive bombshell in the latest episode of "House of the Dragon," which may have complicated the Targaryen family tree even further.

In the latest episode, Rhaenyra (Emma D'Arcy) tries to recruit Targaryen and Velaryon bastards as dragon riders for her army, because only people with Valyrian blood can bond with a dragon.

After the loss of their daughter, Hugh (Kieran Bew) tells his wife that he wants to go to Dragonstone to claim a dragon so that he can have more power to protect their family.

Hugh explains that his mother was a prostitute who was successful because she had the Targaryen's signature silver hair color.

"She used to tell me I was no different to her brother's boys, Viserys and Daemon," Hugh says, seemingly referring to the former king, Viserys I, and his brother, Daemon Targaryen.

Hugh never specifies his mother's name, implying that she was just another illegitimate child of Baerlon the Brave, Viserys, and Daemon's parent.

This claim is strengthened later in the episode when Hugh becomes the only person who is able to bond with Vermithor, the second-largest dragon in the land.

If what Hugh says is true, it is a major departure from "Fire and Blood," the novel that "House of the Dragon" is based on, since it makes Hugh a direct relative of the Targaryen royal family.

Hugh is not directly related to the Targaryens in 'Fire and Blood'

In "Fire and Blood," Hugh is the bastard of an unnamed blacksmith from Dragonstone. Though it is later revealed he has Valryian blood when he claims the dragon Vermithor, there is never a direct link between him and the Targaryens.

In the book, Baerlon only has three known sisters: Alyssa, who he marries; Daenerys, who dies of disease; and Maegelle, who joined the religious group, the faith of the seven.

This is not the first time that "House of the Dragon" has changed the "Fire and Blood" storyline. Fans have praised some of these changes, while others have left plot holes, making the story more confusing.

Hugh's addition to the Targaryens makes an already puzzling family tree even more complicated. It also seems to hint that the show will adapt another major part of the civil war in "Fire and Blood."

In "Fire and Blood," Hugh betrays Rhaenyra and eventually tries to seize the Iron Throne for himself so that he can rule as king.

Hugh is not part of the royal succession in Westeros in the TV series, but the fact that he is related to the royal family and has one of the biggest dragons could give him a genuine claim to the throne. It's not like the Targaryens haven't skipped over generations before.

We will likely find out Hugh's ambitions with his dragon in next week's season two finale.

"House of the Dragon" season two airs Sundays at 9 p.m. ET on HBO and is streaming on Max.