Erryk Cargyll
A knight of the Kingsguard, twin to Ser Arryk ÔÇö he chose the queen, and carried Viserys's crown to Dragonstone in his saddlebags.
A soul born at Crackclaw Point, sworn to The Blacks ÔÇö the Queen's Party, The Kingsguard.
The fuller tale
Season One
Rhaenys is locked in her chambers, courted for Meleys ÔÇö and escapes with Ser Erryk through the crowds being herded to the Dragonpit. Ser Erryk Cargyll arrives with a stolen crown; Daemon sets Viserys's crown on Rhaenyra's head on the shore of Dragonstone.
Where they stand. King's Landing and Dragonstone.
Season Two
Ser Arryk Cargyll is sent to Dragonstone wearing his twin's face; Ser Erryk finds him at Rhaenyra's door. Twin kills twin in the black queen's hall ÔÇö and Erryk, having slain his brother, falls on his own sword for the shame of it.
How it ends for them
On the screen. Fell on his sword for grief (S2┬ÀE2)
He carried Viserys's crown to Dragonstone and chose his queen over his king ÔÇö and then killed the brother who chose otherwise. When it was done he wept, begged forgiveness, and fell on his own sword rather than live with the arithmetic.
On the page. Died of the same duel, weeping (F&B, ch. 3)
Twin met twin at Dragonstone's gates, white cloak against white cloak. The histories cannot even agree which brother struck the killing blows ÔÇö only that both died of the meeting, and that the singers made it beautiful because no one could bear it plain.
In the show, Erryk kills the brother he recognizes beneath the disguise, and the grief of what he has just done overtakes him immediately afterward ÔÇö he falls on his own sword rather than live with having killed his twin, even in defense of his queen.
Fire & Blood records the same double death but leaves the precise sequence of blows genuinely unclear ÔÇö the histories cannot even agree which brother struck which wound first, only that both died of the same encounter, weeping, and that the singers afterward made the story beautiful because the plain truth of it was too painful for anyone to bear retelling straight.
Their chapters, book by book
Where the page and the screen part
The two tellings agree closely on Erryk's actions and their emotional cost; the differences are mainly in pacing and staging rather than substance, with Fire & Blood's account, as with Arryk's, offering more extended detail on the duel's length and anguish than the show's more compressed version allows.
Their journey
Where the two tellings send them to the same place the road runs whole; where they part, the screen keeps the left and the books the right.