The twin brothers of House Cargyll, who we were introduced to in House of the Dragon Season 1, were seen engaged in a brutal duel in the last episode of the second season. Arryk was unleashed by Ser Criston Cole and sent to Dragonstone to assassinate Rhaneyra. However, the queen remains unharmed, and the Cargyll twins become engaged in a bloody conflict. If you're looking for an explanation of Ser Erryk and Ser Arryk's death in HOTD, here's your answer.

House of the Dragon Season 2's first episode ended with the unfortunate demise of Jahaery, son of King Aegon II. The king believes that Rhaenyra has dared to do this terrible thing to him when he has challenged her succession to the Iron Throne. While Aegon II, Helaena, and everyone else in the kingdom mourned the child's death, Ser Criston Cole devised a plan to avenge the sad event.

The Kingsguard approaches Ser Arryk Cargyll as he eats his meal. He tries to provoke Arryk by accusing him of helping Blood and Cheese enter the Red Keep to commit the murder. Aer Criston also says that his twin brother Erryk was a traitor, so he has no reason to believe that Arryk cannot do such a thing. When Arryk senses that Criston Cole can make him appear disloyal to the king, he agrees to be part of the revenge plan.

Criston Cole instructed him to slaughter Rhaenyra by masquerading as his twin brother Erryk, who is a member of the Queen's Council. Arryk does the same, entering Rhaenyra's chamber and drawing his sword. But before he can harm the queen, Erryk enters, and the fight between the two brothers begins. Rhaenyra tells her maid, Elinda, to run and call Ser Lorren to support Erryk. But when Lorren arrives, he can't recognize Erryk out of the two, so he can't do anything.