Daemon Targaryen has found an unlikely ally in Alys Rivers. She could be important in 'House of the Dragon' if her story follows the plot of 'Fire and Blood.'

Alys Rivers is a mysterious, possibly supernatural, character in "House of the Dragon" season two. Here's what to know about her.

• Alys Rivers spends most of "House of the Dragon" season two transforming Daemon's personality.
• Alys is a mysterious, potentially supernatural character in the series and the "Fire and Blood" novel.
• Here's what to know about Alys and her possible future in the series.

Warning: Spoilers ahead for "House of the Dragon" season two and for the book "Fire and Blood."

Alys Rivers has been crucial to Daemon Targaryen's journey in "House of the Dragon" season two, but her agenda is still a mystery. If the series follows her storyline in George R. R. Martin's novel "Fire and Blood," she could be an important player in season three.

The TV series, which is the prequel of the record-breaking "Game of Thrones," has built anticipation in season two by subtly introducing important book characters to bring all the major players on board before the civil war kicks off.

This includes Alys (Gayle Rankin), who first appears in episode three when Daemon (Matt Smith), a fan-favorite lead character, conquers the derelict castle Harrenhal with his dragon. He aimed to build an army from the Riverlands surrounding the castle to win the Iron Throne.

While on his mission, Daemon is constantly distracted by hallucinations that feature his loved ones, including a younger version of his niece/wife Rhaenyra (Milly Alcock), his former wife Laena Valeryon, his mother Alyssa, his brother Viserys, and his nephew/cousin Aemond.

At the castle Daemon also meets Alys, a mysterious nurse living in Harrenhal who seems to be connected to the hallucinations.

In episode three, Alys tells Daemon he "will die in this place" immediately after one of his hallucinations ends, and makes similar strange comments in the following episodes.

In episode six, Alys also appears to help solve Daemon's issues with the Riverlords by potentially murdering Grover Tully, the former paramount of the Riverlands.

This all leads to the season finale when Alys takes Daemon to a spiritual weirwood tree in Harrenhal called the Godswood.

She seems to tell him that all the hallucinations were intended to make Daemon believe in the spiritual world so he would trust an important omen.

When Daemon touches the tree, he seems to see a vision of the future that includes scenes of the Night King, Daenerys from "Game of Thrones," and Rhaenyra on the Iron Throne. It seems to suggest that for the Song of Ice and Fire prophecy to be carried out, Rhaenyra must rule Westeros.

Daemon immediately accepts this prophecy and, later in that episode, submits to Rhaenyra's rule, giving her his army.

But this still leaves multiple questions regarding Alys. Is she actually a witch? Did she manipulate any of Daemon's visions? What is her endgame?

We may find out more in season three, but Alys is an important character in "Fire and Blood," George R. R. Martin's book that inspired "House of the Dragon."

Here's why Alys is a character to keep an eye on in the upcoming season of "House of the Dragon."

Alys becomes Aemond's lover and has his only child

In "Fire and Blood," Alys was a nurse for the House Strong family's children in Harrenhal and could apparently see visions of the future.

When Aemond Targaryen, Daemon's nephew, and Ser Criston Cole take over Harrenhal in the name of Aegon II, Aemond orders the deaths of the members of House Strong because they assisted Daemon. Aemond spares Alys' life, and she becomes his bedmate.

Later, Alys becomes pregnant and claims she is carrying Aemond's child. When Daemon returns to Harrenhal to duel with Aemond, Alys watches both men fight and die in Gods Eye lake.

She then disappears until after the civil war between the Blacks, supporting Rhaenyra's family, and the Greens, supporting Aegon's family, has ended.

At this point, she has taken over Harrenhal with a group of outlaws and claims her son is the rightful heir to the throne, challenging the current king, Aegon III. There were also rumors that she had a dragon inside the castle.

Unfortunately, her story ends there, and she isn't mentioned in the rest of "Fire and Blood."

Since "House of the Dragon" is mostly centered on the "Dance of the Dragons" civil war, we may not find out what happened to Alys and her child. But she may have a larger role in the series since she's already interacting with Daemon.

It is not yet clear whether Alys will be a witch in the series

"Fire and Blood" is written like a history book, so the many accounts never confirm whether Alys is an actual witch or if she uses other methods to make her seem like one.

However, the hallucinations in the TV series lend themselves to the witch theory. It almost seems like Alys is controlling the hallucinations to manipulate Daemon into trusting her.

"House of the Dragon" writer Sarah Hess told Entertainment Weekly earlier this year that the creators decided to use hallucinations to gain insight into Daemon's mind.

"He's not going to therapy. He's not going to sit down and be like, 'I just feel like I lost my mom when I was 2.' It just felt like this really interesting, cool way to get into Daemon's psyche against his will almost," Hess said.