In its Season 3 premiere, House of the Dragon does the impossible. It somehow adds incest to a Targaryen story.

The extra dose of incest comes in a scene between Dowager Queen Alicent Hightower (Olivia Cooke) and her son, Prince Regent Aemond Targaryen (Ewan Mitchell). As Alicent tries to persuade Aemond to head to Harrenhal, which would free up King's Landing to Queen Rhaenyra's (Emma D'Arcy) incoming invasion, he leans in and gives her a long kiss. Horrified, Alicent freezes, not reciprocating but unable to retaliate against her son's sudden advance.

"He's very dangerous, and she can't reject him," Cooke told Mashable during a junket interview.

It's a shocking moment, which is saying something, given that House of the Dragon features a marriage between a brother and sister, as well as one between an uncle and niece. The show has dabbled in mother-son incest before, during one of Daemon's (Matt Smith) Harrenhal visions, but that was a dream. Aemond's kiss is a reality — one that doesn't appear at all in George R.R. Martin's Fire and Blood. (Neither does Daemon's dream of his mother.)

House of the Dragon has hinted at Aemond's Oedipal feelings towards Alicent before. In his interactions with brothel owner and sex worker Sylvi (Michelle Bonnard), he seems to be looking for motherly nurturing. For Mitchell, Aemond's charged interaction with Alicent stems from his issues with affection, dating all the way back to childhood.

"He never felt like he had sufficient love as a child, and kids need that unconditional love to develop a balanced view of themselves," Mitchell told Mashable during a junket interview. "And Aemond, he felt like he was lacking in that department, and so he has a very skewed sense of how to show affection. His perception of it is very flawed."

However, in his attempt to show affection toward his mother, who already fears him, Aemond has worsened that relationship.

"He might have burnt bridges with his mum after that moment, because it's singularly just one of the creepiest actions that he's done — and shocking as well," Mitchell said. "It's in Aemond's DNA to be shocking, and he does it there, he shocks the audience, just in a way that you don't expect."

For Alicent, the kiss is the latest in a series of unwanted advances that have come to define her time in the Red Keep. From her marital rape at the hands of Viserys (Paddy Considine) to Larys Strong (Matthew Needham) fetishizing her feet, Alicent has long been fighting for power in a cage where the men around her only see value in her body: how it can make them feel, or whether it can produce heirs. Now even her own son seems to feel the same way, a realization that becomes another reason why Alicent needs to escape the prison that is the Red Keep. That it's Aemond, her least controllable child, adds an extra layer of worry for Alicent, as well as an extra layer for Cooke to play.

"[Ewan and I] didn't need to do much, because it's such a shocking thing that we had to do," Cooke said. "It felt quite explicit on the page, and I really like working with Ewan. The way he plays Aemond is so different to any other character on the show, and it's so strange that I think Alicent always feels like she's on the back foot with him anyway. So that's all I really had to do, and then just let the shock of that speak for itself."

Mashable Senior Editor Shannon Connellan contributed to reporting to this piece.

House of the Dragon Season 3 is now streaming on HBO Max, with new episodes every Sunday at 9 p.m. ET on HBO and HBO Max.