|The title of this article is conjecture based on information revealed in the A Song of Ice and Fire novels or related material and may be subject to change.
- "Twin brothers even ended up on opposite sides; died with tears on their cheeks as they cut each other down."
Ser Erryk was the twin brother of Ser Arryk Cargyll, who was also a member of the Kingsguard.
Ser Erryk and Ser Arryk Cargyll are mentioned as being twin brothers who ended up on opposite sides of the Targaryen civil war known as the Dance of the Dragons. The twin brothers supposedly met on the field of battle, and died at each others hand with tears on their cheeks.
In the books
In the A Song of Ice and Fire novels, Ser Erryk Cargyll was also the twin brother of Ser Arryk, and both were knights of the Kingsguard.
When Aegon II Targaryen usurped the throne ahead of his sister Rhaenyra, and was crowned king by Lord Commander Criston Cole himself, it split the realm and the Kingsguard itself: three other Kingsguard sided with Aegon II and Ser Criston, but three others fled to join Rhaenyra's Queensguard. Ser Arryk sided with Aegon II, while Ser Erryk sided with Rhaenyra.
Eventually, Ser Arryk was sent to infiltrate Rhaenyra's base of power at Dragonstone castle, pretending to be his twin brother, but he happened to run into Erryk in a hallway. In the ensuing duel, each brother died at the point of the other's sword. In some ways it was a microcosm of the entire Dance of the Dragons: a destructive civil war that set brother against brother, and for which there was no winner but mutual destruction.