Janos Slynt is the commander of the City Watch in King's Landing. He is named Lord of Harrenhal and becomes the founder of House Slynt for his service to King Joffrey Baratheon and the betrayal and arrest of Ned Stark. He is exiled to the Night's Watch by the acting Hand of the King, Tyrion Lannister, for his part in the massacre of King Robert Baratheon's bastard children.
Janos Slynt is the commander of the King's Landing City Watch (also called the "Gold Cloaks"), with almost two thousand men under his command. He is charged with keeping peace and order in the city and quelling unrest.
Janos reports to the small council about the disruptions to the city caused by the tournament to celebrate Lord Eddard Stark's appointment. Lord Renly Baratheon suggests dismissing Janos in favor of someone more competent, but Janos angrily replies he doesn't have enough resources. Eddard offers him twenty of his household guard and commands Littlefinger to find gold to pay for an expansion of the City Watch by another fifty men.
After Eddard resolves to expose Joffrey Baratheon's true birth, he asks for the help of the City Watch. Littlefinger agrees to bribe them into supporting Eddard's plan. Janos tells Eddard that they are with him, but is then seen exchanging looks with Queen Cersei. During the confrontation, the City Watch turns on Eddard and kills his men, allowing him to be taken prisoner. Following Lord Stark's arrest, Janos is named the new Lord of Harrenhal and head of House Slynt by King Joffrey, as a reward for his loyalty. He also attends the execution of Lord Stark.
Lord Janos has been given a place in the small council. During a session that coincides with King Joffrey Baratheon's sixteenth nameday and the official announcement of the end of the longest summer in living memory, he expresses his concern with the influx of refugees fleeing the civil war. He is ordered by Queen Regent Cersei Lannister to bar the city gates to peasants. Later, Janos oversees the massacre of all of the late King Robert Baratheon's bastard children. He personally murders the baby Barra before the eyes of her mother Mhaegen, one of Littlefinger's prostitutes, when one of his men expresses doubt. He also interrogates Tobho Mott, who is being tortured by one of the gold cloaks, about the whereabouts of Gendry and learns that he has joined the Night's Watch and is heading to Castle Black. Janos sends a small party of men after Gendry.
Janos is present at a small council meeting when they receive a request for more men from Lord Commander Jeor Mormont of the Night's Watch. Tyrion has Janos as a dinner guest in the Tower of the Hand. Tyrion dismisses his squire, Podrick Payne, after Janos begins to chastise the boy for spilling wine on his hand. The two exchange compliments and jokes. Tyrion asks about the incident in Petyr's brothel, which Janos calls a nasty business, but necessary. Tyrion feigns agreement, saying that the peace must be kept, before adding that he did not realize the peace depended on killing babies. Janos insists that he was obeying orders. Tyrion says that Janos is right, especially when they are the Queen's orders. Janos is careful to point out that he did not say the orders came from the Queen. Tyrion asserts that no-one else would want to murder King Robert Baratheon's bastards, and Janos says only that Tyrion knows Cersei better than he does. Tyrion asks if Janos has heard the rumors about Cersei's incestuous relationship with Jaime. Janos claims that he does not listen to filth. Tyrion insists that those that believe the rumors would consider Robert's bastards better claimants to the throne than Joffrey. Janos asserts his loyalty to Joffrey and says that the rest does not interest him.
Tyrion says that he appreciates Janos' loyalty and then questions him about the murder of Eddard's men in the throne room, asking if Janos ordered their deaths. Janos says that he did and goes on to say that he would do the same again, because Eddard was a traitor who tried to buy his loyalty. Tyrion says that Eddard was a fool for not realizing that Janos had already been bought. Janos accuses Tyrion of being drunk and says that he will not let Tyrion impugn his honor. Tyrion says that he is not questioning Janos's honor, but denying its existence. Janos stands up and threatens Tyrion, calling him a dwarf, but Tyrion points out Bronn behind Janos. Tyrion elucidates that he intends to serve as Hand of the King until Tywin's return from the war and that he cannot trust Janos as Commander of the City Watch because he betrayed Eddard.
Janos insists that his friends at court will not allow Tyrion to replace him and that they will hear what Joffrey has to say. Tyrion says that they will not and nods to Bronn who summons four gold cloaks. Tyrion tells Janos that he is being sent to take the black and that he will leave on a ship for Eastwatch-by-the-Sea later that night. Tyrion says that he hopes Janos will enjoy the Wall and adds that he found it beautiful in a brutal, uncomfortable way. Bronn tells Janos that the gold cloaks will escort him to the ship, because the city streets aren't safe at night. Janos insists that the men are under his command, and Tyrion explains that Bronn is now commander of the city watch. Janos is dragged off, still protesting about his connections at court.
Janos Slynt has arrived to Castle Black along with Ser Alliser Thorne, who has taken temporary command of the castle. He joins Ser Alliser, Maester Aemon and two other black brothers to listen Jon Snow's testimonies. Slynt is dismissive of Jon's claims, referring to Jon as "the bastard son of a traitor" and argues for his execution. When Jon asks him if he has ever been North of the Wall, he boasts that he commanded the City Watch of King's Landing and grows angered when Jon sarcastically retorts he must have been bad at his job to have been sent to the Wall. Slynt clearly does not believe Jon's report, but it somewhat mollified when he realizes that the other black brothers do.
Janos Slynt warns Ser Alliser Thorne that since Snow is popular amongst the Night's Watch, this will give him an edge over him when a new Lord Commander is elected. Slynt suggests sanctioning Jon Snow's expedition to Craster's Keep so the mutineers may kill Jon.
Much to his disappointment, Jon survives and returns to Castle Black. Janos is later present when Jon urges the Night's Watch to seal Castle Black's tunnel because of Mance Rayder's superior forces.
During the Battle of Castle Black, Janos accompanies Alliser Thorne atop the Wall and oversees the defenses. When Alliser leaves the Wall to help the black brothers under attack by wildlings from the south, he leaves Janos in charge of the Wall's defenses. Janos, having no true leadership experience, begins to break down at the sight of Giants and massive wildling army. Grenn steps in by falsely claiming that Alliser needs Janos back down in Castle Black. Janos either believes him or pretends to as a pretext to flee, allowing Jon to take command. Once down below, Janos locks himself in the kitchens, where he discovers Gilly and her son. When Samwell Tarly returns to Gilly, he discovers Janos still in hiding.
Slynt is present in the courtyard of Castle Black when the dead of the Night's Watch are burned in the presence of the recently arrived Stannis Baratheon.
Janos Slynt remains at Alliser Thorne's side, who has recovered from his wounds. He is later present when Mance Rayder is executed by Stannis Baratheon for refusing to bend the knee
Janos supports Alliser Thorne during the choosing of the 998th Lord Commander of the Night's Watch. He is later laughed at by his fellow black brothers when Samwell Tarly reveals how he cowered in fear in the larder of Castle Black with Gilly and her baby.
During a meeting, Janos is assigned by Lord Commander Snow to take charge of rebuilding efforts at the castle of Greyguard. Slynt rudely refuses before Jon is even finished speaking. The Lord Commander clarifies that this is official command, not an offer. Janos further insults Jon, telling him that he can "stick [his] order up [his] bastard arse." Calmly, Jon orders Janos to be taken outside and calls for his sword. At first, Janos is dragged out to the courtyard believing that this is simply a scare tactic, but he realizes his mistake when he is forced down onto the chopping block. Terrified, Janos begs for Jon to give him a second chance and admits that he was wrong. His pleads for mercy are ultimately futile and Jon beheads Janos with Longclaw as a small justice for the deceased Ned Stark.
Former Commander of the City Watch who earned Harrenhal by betraying Ned Stark, Janos Slynt was banished to the Night's Watch for his involvement in the murder of Robert Baratheon's bastards. Slynt allied himself with Ser Allister Thorne at Castle Black, but hid in the larder when the stronghold was attacked by wildlings. He was executed by Lord Commander Jon Snow when he refused his reassignment to Greyguard.