Alleras has a number of similarities with the enigmatic and mysterious fourth daughter of Oberyn Martell. She says that her father was a Dornish noble, but that he was no lord. Oberyn isn't a lord, he is a Prince, as Dorne still uses the title Prince to refer to members of House Martell. Both Alleras and Sarella claim to be the offspring of a female trader from the Summer Islands.
Alleras is notably skilled with a bow and arrow, which would fit her in with the trend of Oberyn's bastard daughters being trained in the arts of combat. She is also described as having similar features as Oberyn, with a black widow's peak and dark eyes.
It is stated that Sarella was in love with Oldtown, whilst her sister Obara Sand hates the place. When Sarella visited Shandystone with her father, Arianne Martell and Tyene Sand, she turned over rocks and wanted to know everything. This shows that Sarella was an inquisitive person. We also know that Sarella is outside the sphere of influence of Doran Martell, suggesting that she resides outside of Dorne.