Lord Commander Jon Snow is the illegitimate son of Eddard Stark. He was born during Robert's Rebellion and brought back by his father to live at Winterfell and raised alongside his half-siblings, the trueborn children of Eddard and Catelyn Stark. He is 14-years old at the beginning of the series.
Jon is said to have more of the north in him and resembles his father Eddard more than his half-brothers, who have inherited Tully features from Catelyn. Tyrion Lannister observes that Jon has the traditional Stark features in all but the family name. Even at age 14, Jon is lean with dark brown hair and grey eyes so dark they border on black. Many people are able to identify Jon is of Stark blood just by looking at him. Out of all his half-siblings, only Arya Stark and Jon have inherited the traditional Stark look.
Jon was raised by his father Eddard Stark alongside his brothers and sisters to know the ways of honor and duty, and possesses a strong moral compass. He is close with his father and half-siblings, especially Arya and Robb. Jon idolizes his father but is wounded by Eddard's refusal to identify who Jon's mother is, who Eddard will not speak about for mysterious reasons. Eddard's wife Catelyn resents Eddard bringing Jon to Winterfell to raise himself. As a result, Catelyn disdains Jon and treats him coldly. As a result of his illegitimacy, Jon feels like somewhat of an outsider in his family and matured faster than his siblings.
Jon is proven to be highly skilled in combat, especially with a sword. He is able to match Qhorin Halfhand during their duel, although the man planned to die at Jon's hands anyway. He could also match Robb Stark, reportedly, in sword combat. He is a natural leader, which he proves early on in his time at the Night's Watch, and he took on a crucial role in the Battle of Castle Black.
Jon Snow was raised among Lord Eddard's trueborn children. He has a half-brother named Robb, who is slightly older than him, two younger half-sisters named Sansa and Arya, and two younger half-brothers named Bran and Rickon. When Jon was an infant, Eddard brought him back from the war to raise at Winterfell, much to the distress of his wife Catelyn who had recently given birth to Robb at Riverrun. Eddard often mentored Robb and Jon, who are of the same age, and they were trained together by Ser Rodrik, Winterfell's master-at-arms. Jon was also educated by Maester Luwin alongside with the other Stark children. While Jon loves all of his half-siblings, he has especially strong bonds with Robb and Arya. He views Robb as his, "his rival and best friend and constant companion,” and they often played and trained together as young boys. Jon is closest with Arya, who “never seemed to fit, no more than he had... yet she could always make Jon smile."
Jon is present with his brothers when their father executes the Night's Watch deserter. He mentors his younger brother Bran not to look away. When the dead mother direwolf is found in the wood on the way back home, they find a litter of direwolf pups. Eddard and his party want to kill them but Robb, Bran, and Jon object. Jon convinces Lord Eddard to spare the pups and let his siblings adopt them, that the pups are an omen from the Old Gods as the direwolf is the sigil of House Stark. Jon says there are five direwolf pups for five trueborn Stark children, and they are meant to raise the pups. This moves Bran, as well as Eddard, who both realize Jon has omitted himself from the count. When Eddard softly asks Jon if he doesn't want one for himself, Jon refuses. Eddard relents and lets them keep the pups. Jon does not think there is one for himself, but shortly after, he finds a sixth direwolf pup - a silent albino pup - and brings his pup back to the group. Jon names his pup Ghost.
King Robert Baratheon and the royal party come to Winterfell. Though Jon usually sits with his family, he must sit with the squires during this feast. He drinks more than he is used to (at dinner at his father's table, he is only allowed one cup of wine). Eddard's brother, Benjen, arrives at the feast. Benjen is First Ranger in the Night's Watch. As with his father, Jon looks up to his uncle and tells Benjen he wants to join the Night's Watch, pleading with this uncle to convince his father to let him join. Jon is upset when Benjen tells him to wait a few years and father bastards of his own first. Jon shouts that he doesn't want that and runs from the hall in tears. Outside, he meets Tyrion Lannister, who is an outsider in his own way as a dwarf. He tells Jon to never forget who he is and wear his bastardy like armor so it can never be used to hurt him.
When Lord Eddard is to go to King's Landing to be Hand of the King, he must hastily make plans for his children. Eddard wants Jon to stay at Winterfell with Robb, but Catelyn will not have him stay at Winterfell if Eddard goes, telling Eddard that Jon is his son, not hers. Eddard becomes angry with Catelyn, fearing Jon will be shunned in the King's Landing court due to his bastard's name. As Eddard becomes angrier with Catelyn over her refusal to let Jon stay at Winterfell, Maester Luwin interrupts and tells them that Jon had expressed a wish to take the black. Catelyn is pleased while Eddard is shocked and has reservations about letting Jon go. Maester Luwin convinces Eddard to allow it as these are hard times for them all, "His road is no crueler than yours or your lady’s." Eddard reflects for a while, acknowledging that bastard-born individuals can rise high in the Night's Watch and the Night's Watch is an honorable and noble calling, but is still hesitant. Catelyn thinks that Jon can be like a son to Benjen in the Watch and parallels having to let go of three of her children with Eddard having to let go of Jon. Though unhappy, Eddard dispiritedly decides to allow it and will talk to Benjen and Jon. In her thoughts, Catelyn is pleased as this means any possible children Jon may have had will never be rivals to her own grandchildren for the inheritance of Winterfell.
As the Stark family prepares to leave, with Eddard, Arya, and Sansa going south, and Benjen and Jon going north, Jon says his farewells to his siblings. He has a tearful good-bye with a now comatose Bran, who had fallen from a tower. Jon begs Bran not to die. He has a warm good-bye with Robb, making plans to see each other at Castle Black. Then Jon has an emotional farewell with Arya. He gives her a sword he had made for her. When he arrives at Castle Black, Jon is disappointed to find that the Night's Watch is no longer what it once was, having fallen into disrepair and ruin. Though there are ex-knights, nobleborn second sons, and highborn bastard sons still among its ranks, many of its ranks are now staffed by ex-criminals and misfits who took the black to escape execution. The master of arms is Ser Alliser Thorne who takes an instant dislike to Jon. Ser Alliser was sent to the Wall after Robert's Rebellion. It was that or death, so he hates Jon for who his father is and mocks him as 'Lord Snow' for being an illegitimate son with a young lord's upbringing. Jon easily defeats the other recruits in training practice, though they are older and bigger than him. However, Donal Noye, a blacksmith who works in the armory, shames Jon for this. He opens Jon's eyes when he points out to Jon that he has had advantages the others have not had: Jon was raised in a castle with a highborn upbringing and was trained under a master-at-arms his whole life while the other boys did not come from privileged circumstances and have never even held a sword before. Noye warns Jon that if he keeps going down this route, he will make enemies. This forces Jon to realize the rough circumstances the other boys grew up in and he begins training the other recruits himself, earning their respect and friendship.
A new recruit, Samwell Tarly, joins the Watch. Jon learns that despite the fact that Sam is the trueborn heir to House Tarly, his father disowned him as Sam prefers books and hates hunting and fighting. Jon reaches out to Sam and helps him become friends with the other recruits. When Ser Alliser wants to bully and have the soft, bookish, non-combative Sam beaten in training, Jon works to protect Sam and arranges for the other recruits to go easy on Sam. When Jon and the other recruits pass training and are allowed to take their vows, Sam has still not passed training. Jon fears that it will only be a matter of time before Sam is hurt or killed under Ser Alliser's training. He convinces Maester Aemon to take Sam on as his steward instead, pointing out Sam's intelligence and high level of reading and writing. Later, after saving Lord Commander Mormont's life from a wight, Mormont gives Jon his ancestral sword, Longclaw, as a reward. Mormont had the pommel changed from a bear the head of a white direwolf with garnet red eyes. Jon is touched but feels conflicted over accepting the sword. Mormont insists he take it.
When news arrives first of Lord Eddard's arrest, Jon is devastated and overcome with worry for his father and sisters. When Jon learns of his father's execution, he is overwhelmed with grief and decides to desert to go and join Robb's army. He is followed by his friends and persuaded to return to Castle Black, to keep his vow to the Night's Watch. Ser Jeor Mormont knows he tried to leave, but understands why he did it as it was out of love for his family, and tells Jon, "You have not deserted—yet. Here you stand. If we beheaded every boy who rode to Mole’s Town in the night, only ghosts would guard the Wall." He forces Jon to realize there is nothing he can do to bring his father back and fighting by Robb's side will not bring Eddard back from the dead. He explains to Jon how those wars in the south over a throne are nothing compared to what is stirring beyond the Wall, "I will not sit here meekly and wait for the snows and the ice winds. We must know what is happening. This time the Night’s Watch will ride in force, against the King-beyond-the-Wall, the Others, and anything else that may be out there. I mean to command them myself (...) So I will have an answer from you, Lord Snow, and I will have it now. Are you a brother of the Night’s Watch... or only a bastard boy who wants to play at war?” Jon makes his decision and accompanies Mormont beyond the Wall as his squire.
Lord Commander Jeor Mormont leads a ranging beyond the Wall taking 300 men to find Benjen Stark and learn where the Wildlings are going, once and for all. They travel to Craster's Keep and beyond to the Fist of the First Men. Jon is chosen to be part of an expedition, his group is lead by the legendary Qhorin Halfhand. They fight against a small group of Wildlings and Jon kills one of them, but refuses to kill another when he realizes that it is a girl, her name is Ygritte. He takes her as a prisoner instead of killing her. When Qhorin Halfhand leaves Jon to execute Ygritte, Jon cannot find it in himself to do so and decides to free her, because he is not able to kill this girl. Later on, the group is discovered by another group of Wildlings, lead by Rattleshirt. Before they can take Qhorin and Jon captured, Qhorin orders Jon to join the Wildlings and find out what their plans are, therefore Jon should do everything to earn their trust. Ygritte is part of Rattleshirt's group, too. As part of his plan to have Jon infiltrate the wildlings, Qhorin has Jon kill him in one-on-one combat after the wildlings force them to fight. Ygritte believes that Jon is joined the Wildlings.
While Jon searches for a way to escape, he travels with Ygritte, with whom he falls in love, and the others. Jon finds himself conflicted between his love for Ygritte and sympathy for the wildling's plight vs. his duty to the Night's Watch. However, he chooses duty over love and remains loyal to the Watch. They manage to scale the Wall. When Jon tries to leave for the Watch, he is unknowingly saved by his brother Bran, who uses his Warging abilities to allow Jon to escape. Barely alive, Jon makes it back to Castle Black and is devastated to hear of the deaths of his younger brothers Bran and Rickon at the hands of his father's ward Theon Greyjoy.
At Castle Black, Jon is able to warn the Night's Watch of the impending attack. He and Donal Noye mount a defense of Castle Black. Donal is killed in the assault, leaving Jon to dutifully and skillfully lead them to victory, earning the admiration of the Night's Watchmen. However, Jon finds Ygritte with an arrow in her chest. Jon goes to her and holds her in his arms, insisting that the maester can save her. However, Ygritte accepts her death and dies in Jon's arms, leaving Jon grief-stricken.
However, Jon is immediately arrested upon Janos Slynt and Alliser Thorne's arrival, due to his involvement with the wildlings and assassination of Qhorin Halfhand, not believing Jon when he tells them that he was following orders from the Halfhand himself. However, they release him and force him to lead an assassination attempt against Mance Rayder in hopes Jon will be killed himself. However, when Jon meets with Mance, Stannis and his troops arrive before anything can happen. Stannis returns with Jon to Castle Black, where he and his men take station.
Later, when the election for a new Lord Commander of the Night's Watch seems to be favoring Lord Janos Slynt (who has it out for Jon Snow), Sam takes a role in convincing other candidates to drop out in Jon's favor. Thanks to this, Jon becomes Lord Commander, to his surprise.
Jon talks to both Sam and Gilly about them leaving Castle Black. He sends them, along with Maester Aemon and Dalla's son to Oldtown, fearing Melisandre will burn Aemon and Dalla's son for their king's blood. He decides that Sam must learn to become a maester in Oldtown to succeed Aemon as Castle Black's maester.
Lord Commander Jon Snow must contend with several difficulties, including satisfying Stannis, who saved the Night's Watch; dealing with tensions between the various factions at Castle Black; preparing to feed and shelter the Watch, King's men, and the wildlings through winter; as well as prepare against the encroaching threat of the Others, an army of the dead. Janos Slynt attempts to cause uproar amongst the troops by disobeying Jon's orders multiple times. Ultimately, Jon doesn't put up with this and personally executes Slynt. As Jon is trying to save as many as he can from the Others, including his efforts to save the wildlings, these decisions are met with opposition by Bowen Marsh and his other officers. His efforts to ally with and save the wildlings, as well as the aid he provides to Stannis as Stannis is one of the few supporting the Watch, causes contention between himself and a faction of his men. Toward the end of his last chapter, Jon receives a threatening letter from Ramsay Bolton, resulting in Jon announcing his intention to march south and confront Ramsay. Shortly after, Jon hears a scream of agony and rushes to the source. A bleeding Wun Wun has killed Ser Patrek of King's Mountain and as Jon is trying to prevent more loss of life, he is stabbed repeatedly by Bowen Marsh and other black brothers, who attack in tears while muttering "for the Watch". Whether or not Jon survives this attack is currently unknown.