Born to a cadet branch of House Martell established with the legitimization of the surviving Sand Snakes two hundred years ago Moreo, as a third son, with his second brother buried as a Septon, once thought to follow his cousin Aryyn, Prince of Dorne and Lord of Sunspear in becoming a Maester and surpassing him by rising through their ranks, but before he could complete his chain, something disturbed him so greatly in Old Town that he left before saying his vows. He returned to his family's holdings, known among the Orphans and Smallfolk as the Green Martells whether for their holdings along the Green Blood near Planky Town or the patriarch’s greed.
In the years since he served his family by representing the merchants and Lords of Dorne and their interests among the Free Cities and the courts of the Great Houses of Westeros. During his travels, he has amassed a great collection of books, scrolls, and artifacts, and visiting Nobles, Maesters, Septons, and travelers of good reputation are allowed access to his personal library.
Moreo would greatly like to see Dorne rise as an independent kingdom once again, free from the influence of the Iron Throne. He realizes however that Dorne is in no position to declare itself a free kingdom, and so works instead to see that the Northron Lords have as little say in Dornish matters as possible.
He has the typical features of a Salty Dornishman, and keeps his hair short, well curled, and oiled, but his face is clean shaven. His typical dress consists of flowing robes and scarves, with the sigil of House Martell always present. In meetings, he will often wear a number of rings and chains and uses a short throwing spear as a walking stick as a bit of theater.
Prince Moreo worked with Myrios Nestoros in securing funds for the construction of a citadel in Planktown.
Princess Sarella sent Prince Moreo to represent her as an advisor to the small council of King Damon Lannister.