Sansa Stark was a member of House Stark and is the elder daughter of Lady Catelyn and Lord Eddard Stark. Near the end of the War of the Five Kings she is wed to Harrold Arryn and was a key influence in bringing the Vale into the Kingdom of the North.
Sansa was raised in Winterfell with her brothers and sister and accompanied Lord Eddard Stark south to King's Landing when he is named Hand of the King. Upon her father's execution and the commencement of the War of the Five Kings she is held hostage in King's Landing, under the eyes of House Baratheon. Eventually she is whisked away from the capital, just before the Siege of King's Landing by Lord Petyr Baelish.
Petyr brings Sansa to the Vale under the guise of being his bastard daughter. Sansa is revealed to her aunt, Lysa Arryn whom does not write to or relieved her to her mother just yet. Petyr Baelish eventually marries Lady Arryn, but she is murdered shortly after when she is thrown from the moondoor. Petyr assumes control of the Vale and wardship of Sansa's cousin, Robert Arryn.
Petyr eventually reveals his plan to wed Sansa to Harrold Hardyng and reveal her at their wedding. Sansa is wed to Harrold, but quickly learns of Littlefinger's ploy to have the Vale swear fealty to the Iron Throne, rather than Sansa's brother, Robb Stark. Sansa is able to convince her new husband to swear fealty to the North against Littlefinger's wishes and the Vale formally swears itself shortly after. Littlefinger is also found dead soon after, with some saying the deed was conducted by Lord Arryn at his wife's behest.
Sansa ruled the Vale alongside her husband, and her children continued to rule the Vale after his passing.