Sarella spent the better part of her childhood in the Water Gardens, like many children of Dorne. There she was regaled by tales of the Sand Snakes and Prince Oberyn and other heroes of centuries past. From her sheltered life in the palace by the sea, she pictured her own future as one filled with adventure, swordplay, love, and daring, but instead inherited her father's seat at the age of seventeen when he passed away from an illness.
Sarella became the Lady of Sunspear and Princess of Dorne when her father Prince Aryyn Martell died of an illness. She kept Dorne nuetral during the war of the Ascent of the Lion , privately courting the idea of a Dornish independence with her vassals.
Sarella married Martyn Dayne, Lord of Starfall. She plotted with Varyo Velaryon to remove Queen Aeslyn Targaryen in order to replace her with her younger sister Danae Targaryen, who she learned about through letters from the Grandmaester Orin Baratheon who started writing to her after her father's death. Sarella coordinated the release of Martyn and Ulrich Dayne after the Battle at Stonehelm, and the wardship of the former Prince, Rickon Baratheon.
She swore allegiance to the Lannister throne after negotiations with King Damon Lannister in Sunspear. Sarella attempted to assasinate him on his journey back to the captial, but Ser Ulrich intervened, saving the life of the King.
After Danae was crowned Queen of Westeros, the two met in Storm's End and Sarella asked for recompense for her aid in disposing of Aeslyn and securing the throne for the Last Dragon. The two made a marriage pact that their heirs would one day wed. While there, Sarella met with an envoy of Rymar Royce who instructed her to lead Dorne's armies against Myrios Nestoros in order to regain the crown's favor after her failed assassination. In doing so, Sarella solidified a strong alliance with Lys and its new Prince, Varyo Velaryon.
She gave birth to a boy, Lewyn Martell, towards the end of the second era.
After Loren Lannister's death and the victory in Essos, Sarella sailed to King's Landing to take up her post on the small council, bringing her husband with her and leaving Ellaria Uller as castellan of the Old Palace. In the capital, the King caused Martyn to doubt the parentage of his son and when Ulrich was given a trial by combat for oathbreaking, Martyn served as champion and slew his brother. Sarella returned to Sunspear after Ulrich's death, enraged.
Sarella sailed for Dragonstone after learning of the Queen's flight, where she began an affair with Danae and urged her to sever ties to the Lannister King and claim the Iron Throne for herself alone, against the counsel of Prince Varyo. She was eventually rebuffed, and Danae chose to abandon both her plans for war and her romantic relationship with Sarella, flying her dragon Persion to Oldtown to end the War of the False King. Sarella returned to Dorne.
After King Damon Lannister legitimized her oldest half brother Andrey Sand, Sarella called a council of Dornish lords in order to prepare for any threats against her claim. Fearful of his sister's wrath, Andrey fled to Essos, where he was abducted first by a smuggler named Assadora and then later by an Essosi spymaster named Moreo, both of whom intended to use him to stake a claim to the kingdom. Moreo sailed with Andrey to Dorne with a small fleet of warships.
At the same time, open rebellion from House Yronwood resulted in the apparent death of Prince Martyn. Sarella took a former political rival, Maric, as a paramour.
"Sarella Martell is not a woman who treats her visitors kindly." - Damon Lannister
"This woman's rash influence is dangerous...Is she so eager for bloodshed? So desperate to see the kingdoms burn in the flames of a dragon’s breath? You will not find me so easily played as the other cyvasse pieces you have moved, Princess…" - thoughts of Danae Targaryen
"Sarella is simply a child learning the rules of the game outside of her own little desert, and has chosen the largest pieces to play with." - Rymar Royce
"Sarella had the heart of a pit viper, and he would be lucky to leave her lair alive." - thoughts of Andros Sand
“A petty, insecure woman, who thinks that if she fucks someone, she owns them.” - Maric
Martyn Dayne, husband
Lewyn Martell, son
Tyene Martell, daughter
Aryyn Martell, father (deceased)
Gianna Martell, aunt (deceased)
Andrey Martell, half-brother
Mallor Sand, half-brother (deceased)
Trystane Sand, half-brother
Maron Sand, half-brother
Moreo Martell, uncle