Keeping it in the family. 

Warning: Spoilers ahead! Do not proceed unless you’ve watched the “House of the Dragon” Season 3 premiere.

In the Season 3 premiere of the “Game of Thrones” prequel series “House of the Dragon,” Aemond Targaryen (Ewan Mitchell) kisses his mom, Alicent (Olivia Cooke), on the lips. Yikes.

She stands there stiffly, not pushing him away. But her eyes are open, and she looks freaked out. 

After he stops, she gives him an awkward, tense smile. It’s obvious that Alicent is horrified by her son’s bizarre action, but she also doesn’t want to rock the boat by questioning him, or showing disgust.

Incest isn’t new for the Targaryen family – Aemond’s siblings, Aegon (Tom Glynn-Carney) and Helaena (Phia Saban), are married to each other, and have kids together. 

Aemond’s half-sister, Rhaenyra (Emma D’Arcy), meanwhile, is married to her uncle, Daemon (Matt Smith). 

The Targaryen family tree is more of a circle. However, most of the incest is between siblings or cousins.  Even within this family that views it as acceptable, it’s taboo between a parent and child.  

Alicent also didn’t grow up with this family “tradition.” She married into House Targaryen.

She pushed her kids into it, in order to fit in with Targaryen customs. But, judging from her freaked-out expression when Aemond kisses her, she’s not comfortable participating in incest herself. 

Set over a hundred years before the events of “Game of Thrones,” the show follows a civil war between Rhaenyra’s side of the Targaryen family, and Aemond and Alicent’s side, as they fight over the Iron Throne. 

Rhaenyra’s side is often called “Team Black” while Aemond and Alicent side is known as “Team Green.” 

Aemond is now in charge of Team Green as the de facto king, because his badly burned older brother, King Aegon, has run away. Aemond has always been weird, volatile, and bloodthirsty, which is why he’s a fan favorite. When he’s onscreen, drama happens.

Right before Aemond kissed her, Alicent was trying to convince him to leave King’s Landing, and fly his dragon to Harrenhal. 

Unbeknownst to Aemond, Alicent secretly made a deal with Rhaenyra to try to end the war. Alicent promised to open the gates so that Rhaenyra could come to King’s Landing and take the Iron Throne for herself, without bloodshed. 

Alicent promised to hand over Aegon for Rhaenyra to kill. In return, Rhaenyra would spare Alicent, her daughter and grandkids. 

Aemond and Aegon have ruined this plan, as King Aegon goes missing and Aemond rules in his place. Alicent can’t hand Aegon over to Rhaenyra when he’s MIA. And Aemond would never go along with this plan to cooperate with Rhaenyra.

So, Alicent is trying to butter up Aemond and push him to leave King’s Landing, in order to salvage her plan to let Rhaenyra in, and end the war. 

As Alicent tells Aemond that he should have been born first, so that he could have been king all along, he kisses her.

It’s unclear if Aemond kisses his mom out of true romantic desire – that guy is a nut. More likely, he did it as a twisted sign of affection or as a gesture of control. 

“House of the Dragon” airs Sundays at 9 p.m. on HBO.