Something is rotten in the city of King’s Landing.

The sixth episode of HBO’s House of the Dragon raises suspicions about the bloodline of Princess Rhaenyra’s three sons—Jacaerys, Lucerys, and Joffrey. Though Rhaenyra is married to Laenor Velaryon, all three of the young princes have brown hair, instead of the signature platinum locks that the Targaryens and Velaryons are known for.

Here, we explain what to know about her kids’ lineage.

(Beware, spoilers are ahead!)

So, who is the real father of Rhaenyra’s children?

In the show and in George R.R. Martin’s Fire and Blood novel, it is heavily implied that Ser Harwin Strong, a knight and the captain of the City’s Watch, is the true father of Jacaerys, Lucerys, and Joffrey. Harwin, who we first get a glimpse of in Episode 3, bears the same curly, dark brown locks that all Rhaenyra’s boys have.

The show also makes a point of subtly depicting Harwin and Rhaenyra’s romance, with their lingering looks and softened gazes toward each other. Harwin’s fierce protectiveness over Jacaerys and Lucerys during their sword training with Ser Criston Cole—and Harwin’s beating of Criston after he teases that the princes are his sons—also indicates that Harwin himself is aware that they share his blood.

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Does everyone know that Harwin is the father?

The illegitimacy of Rhaenyra’s sons seems to be an open secret in the Red Keep. King Viserys, Rhaenyra’s father, has turned a blind eye to the lineage of his grandsons. When Queen Alicent presses him on the matter, Viserys simply chalks up the children’s physical variations to the spontaneity and uncertainty of nature. Naturally, the rest of the court has taken after Viserys. Even Laenor, Rhaenyra’s husband, hints that he knows the princes are not biologically his children in Episode 6.

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OLLIE UPTON / HBO

Despite the seeming acceptance of the children’s true parents, whispers in the Red Keep intensify following Harwin’s fight with Criston, the latter of whom teased the former about his secret fatherhood. Consequently, the end of Episode 6 sees Rhaenyra and Laenor fleeing the city for Dragonstone in order to protect her sons.

Will Harwin return for future episodes?

It’s unlikely. By the end of Episode 6, Queen Alicent’s political ally, Larys Strong, hires criminals to set Harrenhal on fire. Harwin and his father, Lyonel Strong, both die in the blaze.

Still, his legacy may yet carry on. Episode 6 also shows Rhaenyra’s eldest son, Jacaerys, reconciling with the fact that his paternal bloodline lies with House Strong rather than House Velaryon.