Theon Greyjoy

Theon Greyjoy is a major character in the television series Game of Thrones and its novel counterpart series A Song of Ice and Fire. He is the only surviving son of Balon Greyjoy and heir to the Iron Islands.  When he was a boy of nine, his father crowned himself King of the Iron Islands; this lead to a failed rebellion that resulted in Eddard Stark taking young Theon hostage back to Winterfell.  Though he was there against his will initially, Theon grew to regard the Stark family highly and saw Robb Stark, Eddard's eldest son as his best friend.

Life in the North

At the start of the story, Theon is around twenty years old and is the ward of Lord Eddard Stark, his captor.  He is on surprisingly good terms with the entire Stark family and is apparently not resentful at all.

War of the Five kings

During their journey to King's Landing, Theon offers his service to Robb and goes to his homeland, the Iron Islands, and reunites with his father, Balon.  Balon is convinced that Theon had gone soft and is loyal to the Starks and not his own family.  To prove his father wrong, Theon converts to the religion of the Islands and takes a garrison of men to Winterfell to claim it in the name of House Greyjoy.  Balon again crowns himself King of the Iron Islands and Theon demands his men refer to him as 'Prince Theon.' He easily seizes the castle, and makes Bran Stark submit to his rule.  He executes Ser Rodrick, making him pay 'the Iron Price.'  Bran and his brother Rickon escape in the middle of the night.  He and his men hunt them down, and apparently burn them to a crisp.  This is later revealed to be a ruse.