Doran Martell

"The prince's health forces him to remain at Sunspear. He sends his brother, Prince Oberyn to attend the royal wedding in his stead"

- Lord Blackmont to Tyrion Lannister

Doran Martell is an unseen character in the second season. He is first mentioned in the War of the Five Kings feature in the Season 2 Blu-ray and again in several episodes of Season 4. He is set to appear in Season 5.

Background
Doran Martell is the Prince of Dorne and the Lord of Sunspear. He heads House Martell, the ruling house of Dorne. He's the older brother of the late Princess Elia, who was murdered by Ser Gregor Clegane in the Sack of King's Landing, and Prince Oberyn, known as The Red Viper.

He suffers from a severe case of gout, which prevents him from walking.

Season 2
Tyrion Lannister, the acting Hand of the King, proposes a marriage alliance to Prince Doran, offering the hand of Princess Myrcella Baratheon to be wedded to Doran's youngest son, Prince Trystane, when both come of age. Prince Doran accepts the alliance and Myrcella is sent to Dorne as a ward of House Martell.

Season 4
Prince Doran is expected to arrive at King's Landing for the Royal Wedding. Due to his poor health, however, his younger brother Oberyn travels to the capital instead.

During Joffrey and Margaery's wedding, Tywin Lannister inquires after Prince Doran's health, revealing that he suffers from gout. Oberyn reassures Tywin that his brother is fine.

In the books
In the A Song of Ice and Fire novels, Prince Doran is a cautious, pensive man who does not wear his emotions on his sleeve. He weighs the consequences of every action before he makes them, but whatever action he ultimately takes is therefore very deliberate. Tywin Lannister himself warns that Doran's patience and insistence on long-term planning should not be mistaken for indecision or laziness, and considers him a genuine threat.

Doran was the eldest child and heir of his mother, who by the equal primogeniture laws of the Dornish ruled as Princess of Dorne in her own right. It is unknown what noble House his father was from. He had two younger brothers who died in infancy, thus his two younger siblings Elia and Oberyn were born almost ten years after he was. As a result of their age difference Doran was raised alone, which probably reinforced his tendency to not share his thoughts, though he deeply loved both Elia and Oberyn.

At the time of the War of the Five Kings, Doran has a bad case of gout and has trouble walking, preferring to move in a wheeled chair constructed by his maester. He hides his disability so as to not appear weak to his potential enemies. Instead, while still in command of his wits, Doran has semi-retired to the Water Gardens palace, and delegated much of the day-to-day running of Dorne to his eldest child and heir Arianne.

Doran's gout is bad enough that he has trouble walking, but he is not a complete invalid, and thus he could have come to King Joffrey's wedding if he truly wanted to, travelling by ship or palanquin. His physical condition was just bad enough, however, to make a convenient excuse for not having to go to King's Landing - enough that the Lannisters couldn't overtly express their displeasure that he did not come.

Doran has three children: Princess Arianne, Prince Quentyn, and Prince Trystane, all born of his wife, Lady Mellario of Norvos. Doran married Mellario for love, not as an arranged marriage, however the two of them later fell out of love, and Mellario moved back to Norvos.