ASOIAF Characters not in "Game of Thrones" by Crow-T-Robot

Question 10

Although three of Arianne's half-cousins, the Sand Snakes (the ones who aren't Ellaria's), do make an (unfortunate) appearance in the show, one of them is still left out. This Sand Snake is not in Dorne at all, and is probably in Oldtown, an acolyte to Archmaester Marwyn.

Sarella Sand