From A Wiki of Ice and Fire
Alleras the Sphinx by Cris Urdiales
|Book(s)||A Feast for Crows|
Alleras is described as having a Dornishman for a father and a Summer Islander for a mother, with dark brown skin, curly black hair, a widow's peak, and black eyes. He is slender and comely.
A Feast for Crows
Alleras is in the circle of friends that includes Pate, Mollander, Roone and Armen. He is doted on by all serving wenches at the Quill and Tankard, including Rosey, which makes Pate jealous. He has been at the Citadel for a year, and has forged three links in his Maester's chain, the most recent of which is copper. He displays remarkable skill with a bow.
By the time Samwell Tarly arrives in Oldtown, Alleras appears to have come into the confidence of Archmaester Marwyn. He seeks Samwell out as soon as he enters the Citadel and instructs him to go to Marwyn.
Many fans believe Alleras to be an alias assumed by Sarella Sand, one of Oberyn Martell's bastard daughters known as the Sand Snakes. In addition to known similarities in age, parentage, training, and location, "Alleras" is "Sarella" spelled backwards.
See: Sand Snakes/Theories.