Joffrey Baratheon

"We've had vicious kings, and we've had idiot kings...but I don't know if we've ever been cursed with a vicious idiot for a king!"

- Tyrion Lannister, summarizing King Joffrey. Joffrey Baratheon was a major character in the first, second, third, and fourth seasons. He was played by Jack Gleeson and debuts in the series premiere. Joffrey was the ruler of the Seven Kingdoms, having claimed the Iron Throne after his father, King Robert Baratheon, died. However Joffrey was actually the bastard son of the incestuous relationship between Ser Jaime Lannister and Queen Cersei Lannister. Because of this, his claim to the Iron Throne was challenged by Robert's older brother, Stannis Baratheon. He was formally styled as His Grace, Joffrey of the Houses Baratheon and Lannister, the First of His Name, King of the Andals and the First Men, Lord of the Seven Kingdoms, and Protector of the Realm.

Joffrey was originally betrothed to Sansa Stark, whom he kept captive in King's Landing after he beheaded her father for treason, as Eddard Stark tried to reveal the truth about his parentage. However, he later set Sansa aside in favor of Margaery Tyrell, as part of the new alliance between House Lannister, the primary supporters of Joffrey, and House Tyrell, the ruling house of the Reach whose support helped save King's Landing from Stannis Baratheon's attack.

At his wedding to Margaery Tyrell  (known as the Purple Wedding), Joffrey was poisoned after drinking from his wine goblet. His final gesture as he was dying was towards his uncle, Tyrion Lannister. Upon his death, Cersei Lannister ​arrests Tyrion on the grounds of regicide.

Background
Joffrey is believed to be the oldest son and heir of King Robert Baratheon and Queen Cersei Lannister. In reality, his father is Jaime Lannister, the queen's brother. He has a younger sister, Myrcella, and a younger brother, Tommen - both also the children of Jaime and Cersei. Cersei and Robert made a political marriage alliance after Robert took the throne by force from the Mad King Aerys II Targaryen.

Joffrey takes after his mother in terms of looks and personality, his blonde hair being a subtle clue that he isn't really a Baratheon, who famously always possess black hair even when one of their parents possesses blonde hair. He is usually accompanied by his sworn shield, the formidable Sandor Clegane, who is better known as the Hound. Joffrey is spoiled, arrogant, cowardly, and sadistic.

Season 1
Prince Joffrey accompanies his parents to Winterfell and is betrothed to marry Sansa Stark as part of King Robert's plan unite House Baratheon to House Stark by blood. Both seem happy with the prospect, and Joffrey is charming and polite towards Sansa. However, he shows no sympathy when Bran falls from a tower and is severely injured, and has to be physically chastised by his uncle Tyrion before he will pay his respects to Bran's parents.

While on the Kingsroad to King's Landing, Joffrey is walking with Sansa and chances upon her sister Arya practicing sword play with a commoner, Mycah. Joffrey sees a chance to have some fun with Mycah, who is too scared to move. Joffrey accuses him of assault on a noble girl and makes a cut on his face with his sword, but Arya hits Joffrey, allowing the butcher's boy to get away. When Joffrey turns on Arya, her direwolf Nymeria overpowers Joffrey, injuring him, and Arya throws his sword in the river. Joffrey begs for his life. Sansa offers aid, but Joffrey is angry at her because she saw him weak and defeated. Later, he lies about the incident and says he was attacked in an unprovoked manner. King Robert knows Joffrey is lying, and is disgusted that Joffrey let a little girl disarm him, but agrees to forget about the incident in return for the death of Nymeria. When she cannot be found, Sansa's direwolf Lady is executed instead.

In King's Landing, Joffrey tells his mother about how he would handle the people of the North as she treats his injury. He suggests capturing Winterfell, taxing the people hard and forcing their warriors to join a "royal army". Cersei elucidates the flaws in his plan and warns Joffrey that a king needs to be more careful in choosing his battles. Cersei tells her son that, "Everyone who isn't us is an enemy". She also urges Joffrey to do something nice for Sansa to win back her goodwill.

Eddard Stark discovers that Joffrey isn't King Robert's son and rightful heir, by examining the family history and realizing that black hair is a dominant trait in the Baratheon line. Eddared realizes that Joffrey's true parentage can be attributed to the incestuous relationship between his mother and his "uncle" Jaime Lannister. Meanwhile, Joffrey wins back Sansa's affection by giving her a pendant.

When King Robert Baratheon is grievously wounded in a hunting injury, he talks to Joffrey on his death bed and says he could have been a better father. Joffrey ascends the Iron Throne. He orders that preparations be made to crown him within the fortnight. Eddard refuses to recognize Joffrey's claim to the Iron Throne. He presents a proclamation from Robert making him Regent and Protector of the Realm to enforce his authority, but Cersei tears up the document. Eddard expects Lord Petyr Baelish and Commander Janos Slynt of the City Watch to take Cersei and Joffrey prisoner, but is betrayed. Eddard is taken into custody and his remaining guards and household are murdered.

Sansa is taken captive as well, but Arya manages to escape into the city. Joffrey dismisses Ser Barristan Selmy from the Kingsguard and names his "uncle" Jaime as the new Lord Commander. Barristan is shocked, as the Kingsguard are sworn to serve for life, and it is legally impossible to dismiss one of their members. Joffrey listens to Sansa's pleas for her father, and he agrees to show mercy to Lord Eddard if he admits treason and recants his claim that Joffrey has no right to the throne. Sansa is sure that he will.

Joffrey is present at the Great Sept of Baelor for Eddard's public trial where, due to threats to Sansa's life, he confesses to treason and acknowledges Joffrey as the true king. Joffrey, playing to the crowd, reveals that his mother and his betrothed have both urged him to spare Eddard's life and exile him to the Wall (this deal had been worked out involving Queen Cersei, Varys, Grand Maester Pycelle, the High Septon, and Yoren waiting in the crowd to take him in custody). Joffrey had been told to spare him, but surprises everyone by saying that his mother and betrothed have the weak hearts and constitutions of women, whilst he has no mercy for traitors. He orders Ser Ilyn Payne to bring him Eddard's head. Payne carries out the order, whilst Sansa faints from shock and Cersei - aware this will fuel the war with the Starks - angrily tries and fails to overrule her son. .

Days later, Joffrey holds court. Marillion sings a song he wrote about King Robert and Queen Cersei, which includes lyrics saying that the boar may have disemboweled Robert, but the "lion in his bed" (the Lannisters' sigil is a lion) was the one who tore his balls off. Joffrey is displeased by the song and its insults against his parents. He forces the minstrel to choose between having his hands or tongue removed, then orders Ser Ilyn to instantly carry out the order, ripping out his tongue in front of the entire horrified court. Joffrey and his guards escort Sansa out of the courtroom and he states to her that she will be kept captive there and will still marry him; he also casually mentions that his mother said he should "put a son in you" as soon as Sansa has had her blood. They arrive at the castle's wall, where there are several heads mounted on long spikes - one is revealed to be Ned's. When Sansa is appalled, Joffrey angrily points to another spike carrying the head of Septa Mordane, revealing that he also needlessly killed Sansa's own Septa. She confronts him about his promise to show mercy to her father, but he says it was mercy, as he gave him a quick death. Then Joffrey forces her to look at the severed heads, and he says that he will give her Robb's head on a spike, too, but she retorts, "Or maybe he'll give me yours." Joffrey is infuriated, but restrains himself from striking her as he says "Mother tells me a king should never strike his lady" - so he simply calls on Ser Meryn Trant to strike her for him, and the knight slaps Sansa hard across the face twice. Sansa comes up behind Joffrey on the walkway, obviously thinking of pushing him, though it would mean her death. The Hound realizes this and stops her, under the pretense of wiping the blood off her lip.

Season 2
Joffrey rules with cruelty and arrogant whims while his grandfather Tywin Lannister fights in the War of the Five Kings to secure his hold of the Iron Throne. Joffrey celebrates his nameday with a tourney and continues to torment the captive Sansa Stark, also naming Ser Dontos Hollard as his new fool as punishment to showing up drunk. He is perturbed when his uncle Tyrion Lannister is made acting Hand of the King. Rumors about his parentage begin to circulate and he confronts his mother, Queen Regent Cersei Lannister with them. He asks her about King Robert Baratheon's bastard children and she slaps him. He threatens her life and then arranges for a city wide massacre of the bastards. Tyrion responds by exiling Janos Slynt and installing Bronn as the replacement Lord Commander of the City Watch.

Robb Stark continues to win victories against Joffrey's supporters in House Lannister. Joffrey has Sansa Stark brought into the throne room and before the whole court, threatens to kill her with a crossbow. Instead he orders her publicly stripped and beaten as revenge. Tyrion interrupts the proceedings and criticizes Joffrey, as Sansa is his future queen. When Joffrey says that he is a king and may do whatever he wants, his uncle reminds him that Aerys thought he could do whatever he wanted as well, a thought that led to him being overthrown.

Talking to Bronn, Tyrion decides that Joffrey is at an age when sexual frustration might be an issue, and this could be one reason for his torment of Sansa. He then sends Joffrey two prostitutes, Ros and Daisy, as a belated nameday present. Joffrey forces one prostitute to beat the other as a message to Tyrion that he will tolerate no further interference.

Joffrey attends the departure of his sister Myrcella Baratheon for Dorne as part of a marriage alliance pact. Joffrey is confronted by an angry populace as he makes his way back to the Red Keep. He is struck by thrown cow excrement and triggers a city wide riot by ordering the deaths of hundreds of citizens in response, despite being escorted by only a dozen of his own guards. He barely escapes the riot under the protection of his Kingsguard and Tyrion publicly berates him for his vicious idiocy. He is also dismissive when it is revealed Sansa has been lost in the chaos, demanding she be left to the mob; Tyrion has to point out that the Starks will kill his uncle Jaime in retaliation if she comes to harm.

King Stannis Baratheon sails on King's Landing with a fleet of over 200 ships. Joffrey is determined to fight personally, scaring his mother. Cersei suspects that Tyrion is encouraging Joffrey and plots to blackmail him into ensuring Joffrey's safety by imprisoning his lover. Joffrey tours the sea wall of the city with Tyrion and insists that he will kill Stannis himself. His bravado is undercut by his woeful lack of appreciation of the danger he is in; he stupidly suggests that they should be planning to assault Robb rather than defending their capital.

Joffrey procures a new sword for the Battle of the Blackwater, naming it "Hearteater." He forces Sansa to meet him in the Throne Room before going to the city walls, making her kiss the blade and claiming that when he returns it will have Stannis' blood on it. Sansa carefully undermines his claim by questioning if he will fight in the vanguard. Joffrey is frustrated by not being made aware of Tyrion Lannister's plans to defend the city and angrily threatens his uncle. The absence of the Royal Fleet frightens Joffrey. He is pleased when Tyrion's wildfire explosion decimates Stannis' fleet. However, his courage wanes when he sees the size of the landing force that comes ashore. A sortie led by the Hound fails to drive the attackers back. The Hound then deserts his place on the Kingsguard rather than go back out. Joffrey is relieved when Ser Lancel Lannister tells him that the Queen has ordered him back to the Red Keep and ignores Tyrion imploring him to stay and lead. His cowardly exit damages the morale of the men but Tyrion is able to rally them into a further sortie, protecting the gates from a battering ram. Tyrion is wounded during the fighting but the battle is won by the arrival of a host of House Lannister and House Tyrell soldiers under the command of Lord Tywin Lannister.

Joffrey rewards Tywin by naming him Savior of the City. He also grants a favor to House Tyrell for their aid and Ser Loras asks Joffrey to unite their houses in marriage. Joffrey balks at setting aside his betrothal to Sansa, but is easily convinced in a sham dialogue with his mother and courtiers and agrees to marry Margaery Tyrell.

Season 3
King Joffrey is passing through Flea Bottom in a heavily guarded palanquin. The Riot of King's Landing recently occurred in this part of the city. His convoy suddenly stops moving because his betrothed Margaery Tyrell insists on interacting with the smallfolk and visiting an orphanage. Later that night, he has dinner with Margaery, her brother Loras, and his mother Cersei. Cersei tells Margaery that the king barely survived the recent riot, but Joffrey explains that they were not in any real danger. He also defends Margaery's actions, to Cersei's discomfort.

While fitting clothes in his chambers, Cersei asks Joffrey what he thinks about Margaery, and he says the alliance with the Tyrells will help them defeat the northern rebellion. Cersei asks what he thinks about her personally, but Joffrey dismisses her questions. Later, Joffrey summons Margaery to his chambers. Joffrey is holding his new crossbow and asks why she was married to traitor Renly Baratheon and why she failed to give him a child. Margaery tells Joffrey that she doesn't believe Renly was interested in women. Joffrey says he is considering making homosexuality punishable by death. He then demonstrates to Margaery how to use a crossbow.

Joffrey, Margaery, Cersei, and Olenna Tyrell are visiting the Great Sept of Baelor, where the royal wedding will be held. Joffrey tells Margaery about the history of the dead Targaryen kings. Margaery feigns interest, then they hear a crowd of smallfolk outside. Margaery suggest they greet them, and Joffrey is reluctant but has the doors opened. Joffrey and Margaery step outside to a happy, cheering crowd, while Cersei looks on angrily.

Ros is caught spying on Lord Petyr Baelish, so Lord Baelish gives her to Joffrey, who brutally kills her in his chambers with his crossbow.

Joffrey summons his Hand Tywin Lannister to the throne room. Joffrey asks for a report of the small council meetings, and Tywin invites him to attend the small council meetings. Joffrey complains that Tywin holds the meetings in the Tower of the Hand, which requires him to climb many stairs. Joffrey squirms as Tywin approaches the throne, and Tywin tells him that he can be carried to the tower. Joffrey then asks for information on the rumors about Daenerys Targaryen and her dragons. Tywin confirms the rumors are true, and Joffrey demands to know what is being done about it. Tywin tells him it is not his concern, and he should leave such matters to his advisers.

At the wedding of Tyrion Lannister and Sansa Stark, Joffrey escorts Sansa to the altar. He then removes Tyrion's stool, so he cannot reach Sansa's shoulders to cloak her. Joffrey laughs when Tyrion is unable to cloak her. When Sansa excuses herself from her table during the feast, Joffrey follows her, and suggests he might pay a visit to her chambers that night after Tyrion passes out. Joffrey then calls for the bedding ceremony, and Tyrion insists there will be no bedding ceremony. Tyrion threatens the king, which infuriates Joffrey. Tywin says they can do without the bedding ceremony, and Tyrion says he was only joking.

At a meeting of the small council, Joffrey gleefully informs Tyrion of the deaths of Robb Stark and Catelyn Stark. He tells Grand Maester Pycelle to thank Walder Frey for his service and wants to serve Robb's head to Sansa at his wedding feast. Lord Varys and Tyrion take offense to this, and Tyrion threatens the king again. Tywin interjects by saying that he has won Joffrey's war for him. Joffrey angrily states that his supposed father won the real war, while Tywin hid in Casterly Rock during the fighting. Tywin orders that Joffrey be put to bed, and given Essence of Nightshade to sedate him. Joffrey is taken to his chambers by Cersei.

Season 4
With King Joffrey basking in his "glory", he is not very interested in planning his own wedding. Joffrey insists to Jaime Lannister that the people of King's Landing know that he " saved the city " in the Battle of Blackwater and they know that he " won"  the War of the Five Kings,  and is convinced that there will not be a riot at the Purple Wedding.

At a Breakfast celebration on his wedding day, Joffrey is given various gifts. Among them, he is given a book by his Uncle Tyrion, and a Valyrian steel sword made from the Valyrian steel greatsword Ice, by his grandfather Tywin. Pleased with his gift, he destroys the book with his new sword, to the horror of his guests. He says the sword needs a name, and one of the guests suggests Widow's Wail, which Joffrey approves of.

In the Sept of Baelor at the purple wedding celebration, Joffrey and Margaery are wed and the wedding feast is held shortly afterwards.

At the wedding feast, a band is playing The Rains of Castemere, and Joffrey throws money at the band and tells them to go away. Later, Dontos Hollard performs in front of the royal family and Joffrey promises a gold dragon to whoever knocks Dontos' hat off which leads to many objects hurling at his head. Joffrey then stands up and says that he is only interested in his own way of entertainment and that everyone should contemplate the history of the wedding, so he brings out a surprise; 5 dwarves, dressed as the kings who fought in the War of the Five Kings. The dwarves put on a fight, with the Joffrey imitator coming out on top, whilst Joffrey laughs hysterically, spitting wine all over himself. When the fight is over, Joffrey says that one can not be champion until he has defeated all his opponents, and turns his attention to his uncle Tyrion, saying he should join the fight, mocking him for him being a dwarf. Tyrion replies by indirectly mocking Joffrey of his cowardice at the Battle of the Blackwater, to which Joffrey responds by tipping his wine over Tyrion's head and makes him his new cup bearer. Tyrion picks up Joffrey's goblet but he knocks it on the floor and kicks it away. Sansa picks up the goblet and hands it to Tyrion, who then pours the wine and hands it to Joffrey, who demands that Tyrion kneels before him, but Tyrion refuses. This conflict is interrupted by the arrival of the big wedding pie, which is cut by Joffrey with his Widow's Wail, and doves come flying out of it. While Joffrey is eating his pie, he notices Tyrion trying to leave, but Joffrey commands him to stay and bring him his wine. Tyrion does this and asks to leave, but Joffrey refuses. While this is happening, Joffrey starts to cough, more and more, until he starts grabbing his throat, looking back at Margaery, who says that he's choking. As he gasps for air he steps down from the high table and starts vomiting on the floor. Jaime runs in from the crowd, and Cersei runs from the high table as well. Cersei pushes Jaime away and holds her son in her lap. His face has turned purple, and blood is running from his eyes and his nose. With his remaining energy, Joffrey looks up at Tyrion, pointing at him, and dies. Cersei accuses Tyrion for poisoning her son and demands him arrested.

Personality
Joffrey was cruel, arrogant, sadistic, and a tyrannical ruler. However, he was also incompetent, unintelligent, naive, petulant, cowardly, and prone to rash outbursts of violence. Much like earlier Targaryen kings, it was suspected that Joffrey's incestuous bloodline had resulted in severe defects in his sanity. Nonetheless, Joffrey was consumed by megalomaniacal delusions of grandeur. Even though he was absurdly unskilled at ruling, making far more problems than he solves, he was convinced that he deserves praise and utter devotion from everyone around him. Despite the fact that at the start of the War of the Five Kings most of the realm rises in rebellion against him, to the point that his faction essentially controls only the Westerlands, the Crownlands, and a narrow strip of the southern Riverlands between them, Joffrey was convinced that he was the greatest king in the history of the Seven Kingdoms. Added to what was an unstable personality to begin with, Cersei utterly spoiled and indulged Joffrey his entire life, resulting in him possessing a massive sense of entitlement which knows no logical bounds.

Joffrey was deceitful, but shows even less tact than his mother. He was willing to take advantage of the trust that Sansa Stark initially placed in him, when she was blinded by fantasies of marrying her handsome prince. In general, however, Joffrey was usually too short-sighted to bother lying, often simply committing various atrocities in public, without concern for the consequences.

Joffrey was obsessed with the self-conception that he was a great warrior like King Robert, but displays no martial skill whatsoever. Even the young Arya Stark was able to overpower him. Particularly, despite the fact that his faction was losing the war and bracing for a siege in King's Landing, Joffrey insisted that now was the time to "strike" against Robb Stark, at which Tyrion had to point out that his own city was on the verge of attack by Stannis's superior forces.

Aptly described as a vicious idiot, Joffrey was not simply a ruthless king, but absurdly incompetent. Soon after he was crowned king it rapidly becomes apparent to all that he's an utter imbecile, almost laughably unskilled at even the most basic concepts of ruling and running the realm. While Robert was also not skilled at ruling (though not as bad as Joffrey), he was at least respected as a great warrior. Joffrey, in contrast, had no redeeming values of any kind whatsoever; literally his only claim to rule was that he was the son of Robert, the previous king. The great irony, of course, was that Joffrey was actually Jaime's bastard son and had no valid claim to the throne, but a shockingly large number of Joffrey's followers continue to blindly obey his crazed orders without question.

Despite his noted incompetence, Joffrey did successfully analyze the key weaknesses of the feudal levy system used to raise and train armies in the Seven Kingdoms, and proposes the radical idea of raising a standing Royal Army to address them, although his proposal that the army also be used to subjugate rebellions even when the army might be drawn from those rebellious regions confirms his lack of military experience. He was also concerned about reports that Daenerys Targaryen had hatched live dragons in the east, which his grandfather brushed aside as unimportant. Generally, however, Joffrey only rarely makes a valid insight as a means for the narrative to underscore that everyone else is overlooking something, i.e. "if someone as stupid as Joffrey realized this, it should have been obvious to everyone else".

Quotes
"Killing you would send your brother a message."

- Joffrey Baratheon to Sansa Stark

"You're here to answer for your brother's treason."

- Joffrey Baratheon to Sansa Stark

"The king can do as he likes!"

- King Joffrey I

"Everyone is mine to torment!"

- Joffrey to Tyrion and Tywin

Behind the scenes
Actor Eugene Simon had also auditioned for the role of Joffrey before later being cast as Lancel Lannister.

Gleeson's naturally dark hair needed touching up every single day he shot to keep it Lannister blonde. His hair was also kept short because it makes him look younger.

Gleeson was born in Cork, Republic of Ireland. He is a student of Trinity College Dublin and a member of DU Players. As a result, Gleeson's natural speaking voice actually has a pronounced Irish Cork accent: the upper-class, Received Pronunciation accent he adopts while playing Joffrey on-screen is a conscious part of his performance. In the Blu-ray commentary for "Lord Snow", Sophie Turner (Sansa Stark) explains that for amusement between takes, the English-accented Turner and Irish-accented Gleeson would imitate one another's accents.

Gleeson said his performance was influenced by numerous Hollywood villains, in particular Joaquin Phoenix's performance as the crazed, petulant Emperor Commodus in the movie Gladiator.

On the Season 3 Blu-ray, Joffrey narrates a Histories & Lore video on "The Red Keep".

In the books
In the A Song of Ice and Fire novels, Joffrey is twelve years old when the story begins. He is described as a handsome young man, taller than average for his age, but not especially skilled at arms. His uncle Tyrion occasionally tries to teach him something of politics and learning, but he is uninterested in such matters. He and Robert have a distant relationship, but his mother dotes upon him. Throughout the books, Cersei is willfully blind to Joffrey's insane and homicidal behavior, no matter how ridiculous. Rather than recognize the monster that she has unleashed on the Seven Kingdoms by putting Joffrey on the throne, Cersei embraces the fantasy that he is a great king, or at worst "willful", and chides her younger son Tommen that he should try to be more like Joffrey. Later books also retroactively reveal that Joffrey's siblings Prince Tommen and Princess Myrcella have lived in terror of Joffrey their entire lives. Joffrey killed and skinned several of Tommen's childhood pets, yet Cersei continued to dote on him. At one point Tommen even says that he used to "go away inside" mentally when Joffrey did certain things to him and Myrcella, though the exact extent of what he did (killing his pets or something far more sinister) has not been made clear.

The reason for Joffrey's sociopathic, borderline-insane behavior is suspected to be due to his incestuous parentage, much like some of the earlier Targaryen kings. Joffrey had a distant relationship with his "father" Robert, and his mother spoiled him, but he grew up as a pampered crown prince, thus there does not seem to be any non-biological cause for his mental instability. From a strict technical standpoint Joffrey is not "insane" in the sense that King Aerys II Targaryen was, in that he doesn't have hallucinations or hear voices. Otherwise, Joffrey is a megalomanical sociopath by any measure.

In the second book, A Clash of Kings, Joffrey at several points shoots and kills peasants with his crossbow, for largely imagined insults. When crowds of refugees from the war he started come to the castle gates to beg for bread, he picks them off with his crossbow from the battlements, for daring to consider him "a baker". He then brags about doing this in open court, before having Sansa stripped and beaten in front of everyone. When Sansa asks if he killed any of the peasants, Joffrey matter-of-factly states that of course he did, he was trying to kill them.

Bastardy
Fans sometimes derisively assume that "Joffrey Baratheon" should really be called "Joffrey Lannister", because of his status as the bastard offspring of the incestuous relationship between Cersei Lannister and Jaime Lannister, and not the son of King Robert Baratheon at all. This is actually in error, as according to the customs of bastardy, Joffrey doesn't even have the right to use the surname "Lannister". As Jaime's bastard son, given birth to by a woman from the Westerlands (Cersei), Joffrey would have to use the bastard surname for the Westerlands: "Joffrey Hill". There's also the possibility that he might be called "Joffrey Waters" given that both Jaime and Cersei had been living in the Crownlands for many years, and Joffrey lived his whole life there. All of this, of course, would only happen if Jaime were to openly acknowledge Joffrey as his son, which is an impossibility given the disastrous political fallout this would create. Further, as the product of not merely bastardy, but incest, the Faith of the Seven would want to outright kill Joffrey as an abomination before the gods if his actual parentage were ever revealed. Therefore from a strict legal standpoint, given that Jaime will never acknowledge his children with Cersei, Joffrey has no right to any surname, and should properly just be called "Joffrey" as if he were a lowborn commoner.

Age
Joffrey is stated to be 17 years old in the TV series at the time of the Battle of the Blackwater, as stated in "The Prince of Winterfell". Most of the younger characters in the TV series were aged-up by about two years compared to their book counterparts (i.e. Sansa states that she is 13 years old in the first episode of Season 1, but is 11 in the first novel). Making Joffrey 17 years old in the TV series drastically increases his age relative to the other characters, however, as he is stated to be only 13 years old during the Battle of the Blackwater in the novels (the Tournament he holds in the beginning of book/Season 2 is to celebrate his nameday). This would make TV-Joffrey 16 years old in Season 1, which is stated to be 17 years after Robert and Cersei were married at the end of Robert's Rebellion (which was increased from 15 years ago in the TV series). Cersei also states that she became pregnant with a son by Robert at the very beginning of her marriage who died in infancy. Assuming that Cersei's first son died even a few days after birth, this requires a nine month pregnancy, plus another nine month pregnancy before Joffrey was born (assuming she became pregnant quite soon after her first son died), meaning Joffrey could have been born no earlier than sixteen and a half years before the beginning of the narrative - drastically increasing Joffrey's age to sixteen years old in Season 1 strains the plausibility of this timetable, and drastically increasing his age by four years instead of two like the other characters may have been a dialogue error in "The Prince of Winterfell", in order to make a forced comparison between Joffrey and how Jaime was such a skilled warrior at seventeen that he became the youngest man ever to join the Kingsguard.