Robin Arryn

Robin Arryn is a recurring character in the first season. He is played by guest star Lino Facioli and debuts in "The Wolf and the Lion." Lord Robin Arryn is the only surviving child and heir of Lord Jon Arryn by his wife, Lysa of House Tully. He is the Lord of the Eyrie and the head of House Arryn, the Warden of the East and overlord of the Vale of Arryn. His mother will rule until he comes into his majority.

Background
Robin is the only child of Lord Jon and Lady Lysa Arryn. Jon is the Head of House Arryn, one of the Great Houses of Westeros. He is the Lord of the Eyrie, Warden of the East and lord paramount of the Vale of Arryn. Robin's mother Lysa is the younger daughter of Hoster Tully, the Head of House Tully and lord paramount of the Riverlands. Robin's aunt Catelyn is the wife of Eddard Stark, the head of House Stark and lord paramount of the North.

Robin was born in King's Landing where his father was serving as the Hand of the King for Robert Baratheon. Jon begins an investigation into Robert's legitimate and bastard children and then takes a fever and dies suddenly. Robin inherits Jon's position. Lysa rushes Robin back to the Eyrie following Jon's death. She writes to her sister to accuse House Lannister of poisoning Jon. Lysa is fiercely protective of Robin and he leads an extremely sheltered life.

Season 1
Catelyn Stark brings the captive Tyrion Lannister to the Eyrie. Catelyn has arrested him on suspicion of involvement in the attempted assassination of her son Bran and expects Lysa's support given her earlier accusation. She is shocked to see that Lysa still breastfeeds Robin, despite him being too old. Robin is prone to fits of histrionics, demanding to see "the bad man fly." Lysa calls him a strong and mighty ruler, worthy of the Vale's leadership, but Catelyn appears skeptical.

Tyrion agrees to confess to his crimes and is brought before the High Seat. He presents a list of minor misdemeanours from childhood, though Robin is particularly intrigued by some of them. Tyrion demands trial by combat to prove his innocence and persuades the mercenary Bronn to be his champion. Bronn triumphs against Robin's champion, Ser Vardis Egen and he and Tyrion are allowed to go free. Robin is disappointed at being deprived of an execution.

Catelyn visits Robin and Lysa before leaving the Vale to join her son Robb's army. She asks Lysa to commit the Vale to the war on the side of the Starks and Tullys, but Lysa refuses, saying the Vale's knights are needed at home to defend Robin.

In the books
In the Song of Ice and Fire novels Robin's character is named Robert Arryn. The character was renamed for the television series to avoid confusion with Robert Baratheon and Robb Stark. The name 'Robin' was chosen because it allows him to keep his book nickname of 'Sweetrobin'. Robert is six years old when the events of the books begin. He is a soft, spoiled child but also sickly, suffering from occasional fits. His mother dotes on him a great deal. In the books he is named for King Robert Baratheon.