Jon Snow is the bastard son of Ned Stark. His mother is unknown, although many theories exist on his parentage, including some that doubt whether he is actually Ned’s bloodline. Ned was notoriously secretive about Jon’s birth and died before he could reveal the circumstances to anyone.
He grew up along with the trueborn children in the Stark family and raised a white direwolf named Ghost. He is said to look like a Stark more than any of Ned’s other children. Among the Stark children, Jon had the closest relationship with Robb and Arya Stark. Although Jon had a comfortable childhood and looked up to his father, Ned Stark, Jon never felt truly accepted. By being a Snow, he always felt he was different than the other Stark children. Catelyn also treated him with disdain because he was a constant reminder of Ned’s supposed affair. Her resentment was a constant reminder to Jon that he was different from her trueborn children. Once he reached adulthood, Jon Snow decided to join the Night’s Watch, a decision that was partially influenced by speaking to his uncle, Benjen. Believing he had no place with the Starks as a Snow, he thought he would be a better fit to serve on the Wall.
Jon is a warg, meaning he can control and see through his direwolf’s senses, just like his brother Bran. He is compassionate, brave, perceptive and resourceful. His combat and leadership abilities eventually win him the admiration and respect of his comrades on the Wall. He is compassionate to the other “misfits” on the wall and befriends Samwell Tarly, a new recruit who is well read but hopeless at swordsmanship. When Ned Stark is killed and Robb Stark raises his banners to march on the throne, Jon is torn between his allegiance to his father and family and his vows to the Night’s Watch. Sam Tarly and his other new companions convince him to remember his vows and stay at the wall.
During a scouting trip into the mountains, Jon comes across some Wildling sentries and his party is assigned to kill them. One is a woman, Ygritte, whom he secretly spares against his commander’s orders. His party is later captured by more Wildlings and he and Qhorin Halfhand are the only survivors. He is forced to kill Qhorin to convince the Wildlings he has defected against the Night’s Watch. He does this on Qhorin’s command, so that he can gain the trust of the Wildlings. By doing so, he learns that the Wildlings have amassed a large army of 100,000 wildlings, giants and mammoths. During his time at the Wildling camp, he falls in love with Ygritte and breaks his vows of chastity with her.
Although he’s conflicted over his love for Ygritte and reluctant friendship with Mance and some of the friendlier wildlings, he knows he must return to Castle Black to warn them of the impending attack. In a moment of confusion, he is able to escape over the Wall and warn the commanding Rangers of the wildlings’ army and plan. He also leads a group to re-take Craster’s Keep. Recognizing that the mutineers at the Keep could alert Mance to the dismal numbers holding the Wall, he insists on riding there to eliminate that risk.
Jon Stark is also one of the only main characters in the show who have witnessed the White Walkers and know that they are a very real threat to the Seven Kingdoms.