Gendry is an unacknowledged bastard son of King Robert Baratheon. He is a skilled blacksmith who was traveling with Yoren to the Wall to join the Night's Watch when he was taken prisoner at Harrenhal. He later escaped with Arya and Hot Pie. After meeting with the Brotherhood Without Banners, Gendry decides to stay with the outlaw group until the red priestess Melisandre arrives to bring him to Dragonstone.
Gendry is a bastard son of King Robert Baratheon, but is unacknowledged and unaware of his lineage. Gendry did not receive the bastard surname used in the Crownlands (Waters) because he was not openly acknowledged by Robert.
His mother worked in a tavern and died when he was very young. When he was old enough, an unknown lord paid his apprentice fee so he could learn to be a blacksmith. He spent his whole life in the capital city of King's Landing working as an apprentice blacksmith under his master, Tobho Mott, to forge armor and weapons for the nobility.
Investigating the death of Jon Arryn, Lord Eddard Stark learns that he was seen visiting Tobho Mott's smithy in the city shortly before his death. Eddard also inspects the smithy. Mott tells him that Jon Arryn came to ask about new armor, but he also wanted to talk to the young man, Gendry. Eddard admires a helm that Gendry has made. Mott offers to sell it to him, but Gendry insists that it is not for sale as he made it for himself. Eddard learns that Jon wanted to know about Gendry's mother and realizes that Gendry is the bastard son of King Robert Baratheon. Eddard is at a loss as to why Jon Arryn was trying to track down Robert's bastards.
After King Robert died, the secret payments to Mott stopped so he kicked Gendry out. With no other options, Gendry decides to join the Night's Watch, and is one of the latest batch of Yoren's recruits for the Wall. He meets Arya Stark (disguised as the boy "Arry") when some of the other boys harass her about her sword. When Hot Pie bumps into him, he scares the boys off saying "When I hit that steel it sings, are you gonna sing when I hit you?"
Gendry travels north on the Kingsroad with Yoren and his recruits, befriending Arya on the journey. He is targeted by the City Watch of King's Landing because of his status as a bastard of King Robert Baratheon but remains unaware of his lineage. Yoren intimidates a pair of goldcloaks who come looking for Gendry into leaving empty handed. Gendry sees through Arya's disguise and recognizes her as a girl. She confides her identity and swears him to secrecy. The goldcloaks return with Ser Amory Lorch and a force of Lannister soldiers. They kill Yoren and capture Arya and Gendry. Arya manages to convince them that Lommy Greenhands was Gendry because he was carrying the bull's head helm Gendry made.
The prisoners are taken to Harrenhal. They are brutally tortured by Ser Gregor Clegane's men while being questioned by the Tickler. Gendry is selected as his next victim but is saved when Lord Tywin Lannister arrives and asserts that the prisoners are more useful alive.
Gendry is put to work at the castle's forge. Both the Tickler and Ser Amory are killed in suspicious circumstances. The deaths prompt Tywin to launch an investigation and he ultimately blames the Brotherhood Without Banners. Tywin leaves Harrenhal to march on the Westerlands. Arya arranges for Jaqen H'ghar to help them to escape the castle.
After escaping Harrenhal with Arya and Hot Pie, they are all captured by the Brotherhood without Banners.
While they are with the Brotherhood, Gendry helps them out by fixing some armor.
Upon learning of Gendry's desire to remain with the Brotherhood, Arya is distressed, and confronts him about it, as she had intended to bring him with her back to the Starks. Gendry explains that the Brotherhood is the closest thing he's had to a family. When Arya states that she could be his family, he reminds her that she's still the daughter of a great house and he's one of the smallfolk: she wouldn't be his family, she'd be his lady.
Gendry is out and about with Arya and members of the Brotherhood when Melisandre arrives. Arya grumbles about the presence of the red priestess, asking what all the fuss is about; Gendry quips that Arya doesn't see because she's a girl. Gendry is shocked when the Brotherhood turns him over to Melisandre in exchange for two bags of gold.
As he and Melisandre quietly traverse Blackwater Bay, she finally reveals the truth of his heritage to him by pointing out the Red Keep and identifying it as his father's house. Upon arriving at Dragonstone, Melisandre puts Gendry up in a lavish chamber and seduces him. She quickly turns the tables, tying him to the bed and proceeding to leech his blood for a ritual.
Following the incident, Gendry is relegated to a cell beneath the castle. Davos Seaworth visits him and the pair discuss the hardships of growing up in Flea Bottom. Davos asks why Gendry trusted Melisandre, to which the blacksmith admits he's never been with a woman, so although the trap was quite obvious, he took a chance. Later on, Ser Davos frees Gendry and sends him back to King's Landing in a rowboat, the only way to discreetly leave Dragonstone, although Gendry admits he doesn't know how to swim and has never been in a rowboat before.
When Stannis's army becomes snowbound on the march to Winterfell, Melisandre suggests that they sacrifice more king's blood to the Lord of Light, and Stannis initially believes she is referring to Gendry before he realizes she is referring to his own daughter, Shireen Baratheon.
After smuggling Tyrion Lannister into King's Landing near the Red Keep to meet with his brother Jaime, Ser Davos Seaworth, now a principal advisor to the bastard King in the North Jon Snow, finds Gendry in a forge on the Street of Steel. Already fed up with serving the family who murdered his father, Gendry readily agrees to come with him, bringing a war hammer with a stag sigil carved into it before leaving. As they prepare to leave, two Gold Cloaks arrive to inspect Davos's boat, and Gendry remains on guard while Davos bribes them into leaving. When the guards return after noticing Tyrion, Gendry kills them with his hammer, allowing the trio to escape.
Upon returning to Dragonstone, Davos urges Gendry to keep his identity a secret and go under the alias of Clovis, but Gendry immediately introduces himself to Jon Snow as Robert Baratheon's bastard son. He notes how their fathers - Robert Baratheon and Eddard Stark (Jon's true parentage still being unknown to all) - trusted each other, were good friends, and fought together. Jon and Gendry talk about their fathers and get along well. Gendry offers to accompany Jon on his expedition beyond the Wall and Jon accepts his help.
At Eastwatch-by-the-Sea, Gendry warns Jon not to trust the Brotherhood, having been sold to Melisandre by them. Nevertheless, he accompanies the party north of the Wall to confront the army of the dead.
North of the wall, Jon asks if Gendry has ever been so far north. Gendry responds by saying he has never even seen snow before. He wonders how the wildlings even survived north of the Wall, to which Tormund jokingly gives him three options: walking, fighting and fucking.
Later, Thoros of Myr asks Gendry if he is still mad with the Brotherhood without Banners, for selling him to Melisandre instead of letting him join them. Gendry angrily responds he does, stating that she stripped him of his clothes and tied him up to a bed. Sander "The Hound" Clegane tells him that sounds pretty good to him, and tells Gendry to stop whinging, explaining that Beric Dondarrion has been resurrected six times and never complained once. Beric himself admits that they were at war, and needed money to keep waging it.
Some time later, Gendry and the rest of the company get caught in a blizzard. Suddenly, they spot a massive polar bear in the distance. The bear also notices the group, and stares at them. Gendry sees its eyes and asks if bears have blue eyes. The bear charges at the group, taking out a wildling that accompanied them. Realizing they were about to fight an undead bear, the group huddles up and gets ready for combat. The bear attacks, wounds Thoros and kills some more wildlings until Jorah Mormont is able to stab him to his death. After patching Thoros up, the group continues on their Wight Hunt.
Eventually, the group stumbles upon a small faction of wights, led by a white walker. Gendry aids the group in their trap, taking down some Wights with his hammer. Eventually, Jon Snow is able to kill the White Walker, and all of the wights except for one perish on the spot. They succesfully capture the wight, but not before he could scream for help.
Jon realises the army of the dead is coming, and orders Gendry to run back to Eastwatch to send a raven to Daenerys Targaryen, asking for aid. Tormund convinces Gendry to leave his hammer behind, as he would be faster without it. After lending his hammer to Sandor, Gendry leaves.
Some time later, Gendry arrives at Eastwatch-by-the-Sea. Having run the entire time, he is exhausted and stumbles in the ice. He tries to get back up, but doesn't find the power to do so. However, it turns out Gendry fell right before the entrance to Eastwatch, and is saved by Ser Davos, who asks what has happened to the others. Exhausted, Gendry tells them to send a raven to Daenerys, completing his mission.
After Daenerys saves the remainder of the group that went beyond the wall, Gendry parts ways with Beric Dondarrion and Tormund Giantsbane, leaving on the Targaryen ship with Jon, Daenerys, Davos, Jorah and The Hound.
Robert Baratheon's bastard son, Gendry trained as a blacksmith in King’s Landing. Upon leaving the city to join the Night’s Watch, he met and befriended Arya Stark on the road north. The two separated when Melisandre brought Gendry back to Dragonstone as a sacrifice for Stannis Baratheon. He escaped death when Davos Seaworth set him free. Davos rediscovered Gendry back in King’s Landing, and enlisted him to join the mission beyond the Wall.
King Robert's actual son Gendry is everything that his alleged son and heir Joffrey Baratheon was not - beyond simply his physical appearance, but also his character and temperament. Joffrey was an arrogant, sadistic fop, with a massive sense of entitlement. He was not skilled at anything - particularly not at combat, in which he was also a coward when faced with real danger. Joffrey's one real claim to importance was that he was Robert's son - which was itself a lie. Gendry, in contrast, is his exact opposite: a generally humble and polite working-class blacksmith who didn't grow up rich in a castle, and a brave and capable fighter when his friends are in danger. He also needlessly defends the boy "Arry" when he sees the other recruits picking on (what he thinks is) a smaller boy. Unlike Joffrey, who thought the throne was his by right but was utterly unsuited to rule, Gendry has many qualities which would make a fine king, but doesn't even know he has a potential claim to it. Growing up having to work for a living, at Mott's smithy, Gendry also grew up disciplined, and doesn't have any of his father Robert's negative qualities of self-indulgence (in food, drink, and women).
Gendry is notably an extremely pragmatic and practical young man, as evidenced by his ability to understand how social standing benefits people unlike him: he understood that if he returned to Riverrun with Arya, she would be his 'lady' rather than his friend. This sets him further apart from Joffrey, who outright fell back on social standing and had massive delusions of grandeur where his own position was concerned. Joffrey accentuated his title as king to be the reason that he should get his way, whereas Gendry fought and survived for other people and was not as arrogant or temperamental as Joffrey. Also, he was surprisingly self-reproachful about his own actions, shown prominently in the aftermath of Melisandre seducing him; Joffrey was not the slightest bit self-reproachful, never blaming himself for anything even if he were the central catalyst for an incident. Joffrey would brutalize women at court, taking out his frustrations by having his guards publicly beat Sansa Stark and citing his authority as king when Tyrion Lannister confronted him about it. In a direct parallel, Gendry is polite and deferential to her sister Arya Stark when he learns who she is, worried at his behavior and insisting on addressing her with formal titles.
Gendry is still somewhat self-conscious about being a commoner, with a commoner's lot in life. Like many of them, he is terrified and subservient when he encounters members of the nobility, while somewhat resenting the great lords for oppressing the lower classes and tearing Westeros apart with their bloody wars. Nevertheless, he readily agrees to help the King in the North Jon Snow, both for his mutual dislike of the Lannisters and his father's past alliance with the Starks.
Though he has no formal combat training, Gendry is remarkably skilled with a hammer, both as a weapon and a tool. While escaping from King's Landing, he effortlessly killed two curious Gold Cloaks with a war hammer, having inherited his father's incredible strength. This strength has been a prevalent factor throughout his life, as he commented to Hot Pie that when he strikes steel with a hammer it 'sings'. A glaring difference between him and his father is that Gendry does not love fighting, whereas Robert Baratheon absolutely lived for fighting.
Gendry seems now to take some pride in his Baratheon blood, hating the Lannisters for killing his father Robert and immediately informing Jon Snow that he is Robert's bastard son, knowing his father and Jon's (adoptive) father were best friends.