Harrold "Harry the Heir" Arryn nee Hardyng was a member of House Arryn and was the last remaining kin to Jon Arryn within the main line. Near the end of the War of the Five Kings, Harrold was wed to Sansa Stark and was brought into the folds of the Kingdom of the North.
Harrold was born in the home of Hardyng, by his father, a Hardyng, and his mother, an Arryn. He became a ward and squire of House Waynwood at an early age and was raised largely by House Waynwood. When Jon Arryn mysteriously died in King's Landing, Harrold was named heir to the Vale in the event that Jon's sickly son, Robert Arryn died before bearing his own children.
At the age of sixteen, Harrold participates in a melee and wins, earning his knighthood by Yohn Royce. As the end of the War of the Five Kings seems to be on the horizon, Harrold's guardian, Lady Anya Waynwood, enters into a marriage pact with Lord Petyr Baelish. Harrold is wed to the revealed Sansa Stark in a ploy by Baelish to bend the knee to Renly Baratheon. Sansa, however, manages to convince Harrold to bend the knee to her older brother, Robb Stark. Baelish was found dead mysteriously afterwards, with many rumors circulating around his death.
Harrold ruled the Vale with Sansa for years following this, and his children continued to rule the Vale after his passing.