It could be said that the Dance of the Dragons began in House of Dragons due to a mistake that Alicent made. She believed Aegon was the rightful heir because Viserys changed his mind. Only she didn’t notice the conversation Viserys thought she was still having.
Caution: This post contains major spoilers for House of the Dragon Season 2, Episode 3
In the last episode, Rhaenyra found a way into King’s Landing. Realizing that Alicent doesn’t really want a dragon war, she decided to see if she could change her former friend’s mind. That wasn’t the case, but Rhaenyra understood why Alicent has been so adamant about putting Aegon on the throne.
Alicent is certain that Viserys changed his mind about Rhaenyra being queen. After some coaxing, he finally shared his final words with Rhaenyra. When he said “The prince that was promised,” Rhaenyra’s eyes widened. The Aegon Viserys was talking about wasn’t her son at all, but she could understand why Alicent would make the mistake.
Rhaenyra shared that “The Prince That Was Promised” was part of an old story her father told her. She mentioned that it was about Aegon the Conqueror, and not the Aegon who is Viserys and Alicent’s son. This is the Aegon Viserys was talking about. It was a relief to Rhaenyra, but it doesn’t stop the war.
You could see on Alicent’s face that she had realized the mistake she had made. She couldn’t admit it in front of Rhaenyra, but this is something that will be on her mind now. Alicent’s mistake has led to the Greens seizing power and putting Aegon on the throne. That mistake led to the hasty coronation, Luc’s death, and Jaehaerys’ murder.
If it weren’t for Alicent, none of this would have happened. Everyone would have had no choice but to put Rhaenyra on the throne. And Alicent can’t admit it now. She’s telling her son that everything he’s done is wrong, and we’ve seen how Aegon acts. He’s a man-child who doesn’t deserve the crown and is listening to the wrong people.
So Alicent can’t do anything. The only thing she can do now is live with the guilt of everything that happens around her. Rhaenyra was right that it was always meant to be her.