Cersei Lannister/Synopsis

The synopsis for Cersei Lannister from the A Song of Ice and Fire book series and its HBO adaptation Game of Thrones.

History
Cersei was the eldest child of Tywin Lannister, Lord of Casterly Rock, Warden of the West, and Hand of the King, and of Joanna Lannister. She had a twin brother, Jaime. Since a very young age she and Jaime were engaged in an incestuous sexual relationship until they were discovered by their mother. She moved Jaime's chamber to the other side of the castle, and put a guard outside Cersei's chamber. Joanna was merciful and didn't tell anything to her husband, warning the twins to never do such thing ever again, or else she would be forced to tell Tywin. Joanna, who was friend with Doran's mother, tried to have one of her children married to Oberyn or Elia, but she died before that. Lady Joanna died while giving birth to Tyrion, who was a dwarf, and Tywin rejected the marriage proposal of the Princess of Dorne, saying that Cersei was promised to Rhaegar, and offered Tyrion to Elia instead, which the Princess took it as an insult.

During the Tournament in Honor of Viserys' Birth, which was held by Tywin to restore his damaged friendship with King Aerys, Cersei's father intended to marry her to Prince Rhaegar Targaryen yet King Aerys opposed the marriage. Jaime loved both his siblings, but he always hated Cersei's bad side. She hated Tyrion because his birth caused the death of Joanna, while Jaime knew it was beyond Tyrion's control to avoid their mother's death. Cersei's hatred towards Tyrion increased after the prophecy of a witch of the westerlands known as Maggy the Frog. When her aunt Genna told her about her father's intention of betrothing her to Rhaegar, Cersei went to the woods of Lannisport with her friends Jeyne Farman and Melara Heatherspoon to meet the witch Maggy the Frog. Jeyne fled before she could hear Maggy's prophecy.

Maggy correctly predicted Cersei's marriage and mutual infidelity with a king. She went on to prophesy that Cersei would outlive all her children, who would die as kings and queens, and that after everything she had was taken away by a younger and more beautiful queen, the valonqar (High Valyrian for “little brother”, possibly Tyrion, Jaime, or the Hound, according to Bran's visions) would come to end her life. Cersei is frightened by this prophecy. Her friend, Melara Hetherspoon, who had been present, suggested that if they never spoke about it, the prophecies (which included Melara's death) would not come true. Cersei, later in life, recalls how Melara died shortly after their visit to Maggy, and it is heavily implied, though never confirmed, that Cersei killed Melara, to prevent the girl from speaking of the prophecy. Cersei has always identified the valonqar as Tyrion, and eventually comes to worry that Margaery Tyrell might be the younger and more beautiful queen. Ever since Cersei started developing paranoia. She cried once she learned the King refused Tywin's marriage propose with Rhaegar.

Years later, Lord Tywin and Lord Hoster Tully were discussing a marriage between the 15-year-old Jaime and Lysa Tully in King's Landing, and Cersei warned Jaime about it. Jaime already knew Lysa from his visit at Riverrun and was more interested to meet the Blackfish than talking with the shy Lysa. The elderly Kingsguard, Ser Harlan Grandison died, and to avoid the marriage, Cersei urged Jaime to ask to join the Kingsguard, so that they could remain close in the capital. Jaime realized that he had to renounce to his future lordship of Casterly Rock but he accepted. That same night they had passionate sex. A month later, Jaime received news at Casterly Rock that he had been accepted. Jaime joined the Kingsguard during the Tourney at Harrenhal, much to the paranoid Aerys' satisfaction since he had Jaime as a hostage against Tywin and slighted him at the same time. However, Cersei's plan wasn't a complete success, as Lord Tywin never forgave Aerys for this and resigned his position as Hand of the King with the excuse of illness and took Cersei with him back to Casterly Rock, dividing her with her twin brother once more.

Some months after it a rebellion against King Aerys II took place, led by Lord Jon Arryn and Lord Robert Baratheon. The Lannisters maintained neutrality until the very ending of the war when Tywin sacked Kings Landing and Jaime murdered Aerys. Robert Baratheon was crowned as king and, to secure her father’s loyalty, married Cersei. Jaime was part of the honor guard that brought her to King's Landing and him and Cersei had sex the morning of her wedding. Cersei was happy and enthralled by the happy crowds; initially she was exited to marry the hero of the rebellion and the new king, but Robert never cared about her. Since Robert called her "Lyanna" during their wedding night, her fondness for him died right in that moment. Their marriage became a loveless one as Robert only loved his deceased fiancée Lyanna Stark. Cersei resumed her incestous relationship with Jaime and she aborted every child she had with the King, not willing to give him a child, as she strongly resented him.

During the early years of their marriage, Robert would often ask Cersei to come hunting with him, though she would often decline, as Robert's trips allowed her more time with Jaime. Two of Robert's maternal uncles of House Estermont had remained at court for half a year following Cersei's marriage and Robert wanted to repay the visit with a two-week stay at the island of Estermont. There, at Greenstone, Cersei suspected that Robert was having sex with his cousin and had Jaime following him to confirm those suspicions, while she had sex with him as well. Cersei likes to believe that it was at Greenstone that Jaime impregnated her with Joffrey.

Cersei's relationship with Robert continued to detoriate. While Robert "claimed his rights" frequently during the early years of their marriage, his drinking led to him hurting Cersei during those encounters. When she confronted him once during their first year of marriage, Robert claimed it was because of the drink, and he was not to blame. When he tried to take another horn of ale, Cersei smashed her own horn in his face, chipping his tooth. Robert claimed not to remember anything of those nights, but Cersei believes otherwise, and is certain that Robert did recall what he did to her, but felt that pretending to forget was easier than facing the truth. Cersei, in turn, tried to pretend that Robert was Rhaegar during those years. Over time, Robert came to Cersei's bed less frequently, not even once a year.

Robert was never loyal to his queen as well, and bedded many other women and fathered many bastards. True to Maggy's prophecy, Cersei had 3 children, while Robert sired several bastards. After Crown Prince Joffrey had assaulted a pregnant cat, Robert suggested bringing a bastard daughter of his to court. Cersei threatened the girl, claiming King's Landing was a dangerous place for a girl growing up. Though Robert had hit her for that, the girl was not brought to court, and all of Robert's bastards were kept out of sight. According to Petyr Baelish, however, there are rumors that Robert fathered twins on a serving woman at Casterly Rock in 295 AC, and that Cersei had the babes killed, and the mother sold to a slaver. Cersei  Robert and Cersei hated each other and she would complaining about Robert's behavior all the time along with his brother and rival Lord Stannis Baratheon. In fact, because of their personalities, Cersei and Stannis were the most despised persons in court. Jaime and Cersei were are the true parents of Joffrey, Myrcella, and Tommen, the royal children, and the true parentage remained a guarded secret for years. Lord Stannis however had his suspicions, but since Robert had no love for him, he told Jon Arryn to investigate the matter.

Lord Arryn and Lord Stannis visited various bastards at King's Landing and their appearance caused Jon to start agreeing with Stannis. After the tournament held to celebrate Joffrey's twelfth nameday, Cersei and her children traveled with Lord Tywin to Casterly Rock. During the fortnight following the tourney, Arryn was poisoned and fell ill, and eventually died before he could act. While Cersei was innocent of the fact, Stannis blamed her for Arryn's death. Cersei started to worry about her husband and wanted Jaime to be the new Hand, as she was fearing that Robert was going to give the office to one of his brothers, Lord Stannis and Lord Renly. Cersei and Jaime viewed Stannis and Renly as more ambitious and smarter, but luckily for them King Robert had not much love for his brothers. Robert decided to recruit his childhood friend Eddard Stark as Hand of the King, angering Stannis who thought he was owed the position through his 15 years of service on the small council and left King's Landing for Dragonstone with most of the royal fleet and left Robert and Renly surrounded by Lannisters. At the same time, Lady Lysa Arryn, Jon's widow, fled from King's Landing with her son Robert Arryn and most of her household and retinue of knights to prevent the King from sending her child to foster at Casterly Rock. The paranoid Lysa would later summon various knights of the Vale to come at the Eyrie and gather swords.

During the king's visit in Winterfell, Cersei is humiliated in public by Robert as usual with him having encounters with other women and order and immediate visit to Lyanna Stark's tomb as soon as they arrived. Cersei stays in the castle during one of Robert's hunting trips, and have one of her usual sexual encounters with her brother. Ned’s son, Bran, saw Jaime and Cersei having sex at the abandoned ruined tower, while discussing fishy matters about Eddard, Stannis, Renly, and Lysa. In an attempt to conceal the truth by trying to kill him, Jaime threw Bran of the window. While they were travelling back to King' s Landing an assassin tried to murder an unconscious Bran rising suspicion on the Lannisters (who had however nothing to do with that). Lady Catelyn, Ned’s wife, kidnapped Lord Tyrion Lannister which caused a war between Lannisters and Tullys.

Ned, investigating Arryn’s murder found the truth about Cersei’s children and led by honor warned her about the risk under which she would fall once Robert Found out. Before Ned could tell Robert, however, Cersei murdered her husband by causing him to get excessively drunk during boar hunting. Actually Cersei had already instructed her cousin Lancel to give the strong wine to Robert before Ned found the truth. Robert started to worry Cersei the last years and months: he had become too loud and short-tempered. He was out of control and stopped listening to his wife. Moreso Stannis and Renly started to plot against her and her children, but she knew Robert's brothers were too smart for her and was afraid of both of them, so she didn't even dare to deal with them. Cersei never wanted Jon Arryn to die, as she needed honorable men as Hand of the King, while Stannis, Renly, Petyr Baelish, and Varys were dangerous. Cersei decided to kill Robert out of fear that Ned might find the truth since Pycelle told her that he had the book about the great houses, also Cersei hated Robert a lot, since she learned he was never going to love her. Ned admitted to feel sorry for both Cersei and Robert, but still refused Cersei's sexual advances and told her to flee to the Free Cities with her children. Cersei wasn't happy, as she hoped to have Ned remain as a loyal Hand or just return to Winterfell and leave her family alone.

When he saw his old friend grieving in pain, Ned was taken by mercy and failed to tell him the truth about his children. While Robert's youngest brother Renly fled from the capital with his men and Tyrells men, Ned acknowledged Stannis Baratheon as Robert's rightful heir and refused Cersei's eldest child, Joffrey, as the rightful heir. Joffrey was named king while his mother imprisoned Ned Stark for treason with the help of the commander of the City Watch, Janos Slynt. Cersei has her hostage, Sansa Stark, writing 3 letters: one for her brother in Winterfell, Robb Stark, another for her grandfather in Riverrun, Hoster Tully, and another one for her aunt at the Eyrie, Lysa Arryn. All of them are commanded to ride in King's Landing and swear loyalty to King Joffrey I.

Joffrey forced Cersei to fire Ser Barristan Selmy, since he needed someone to blame for Robert's death. The only thing Joffrey cared about were torment and punish those who viewed as enemies, leaving the realm under the rule of the small council. This caused Joffrey to be nothing more than a mere uncontrollable puppet of the other lords.

Later, during the War of the Five Kings her brother Jaime was captured by the northmen during the Battle of the Whispering Wood. The Lannisters wanted to end the problem with the North pacifically, as their biggest threat were the ambitious infamous brothers of King Robert, Stannis and Renly. Tywin, Kevan, and Cersei intended to use Lord Eddard to buy peace with the Starks, yet Joffrey had him executed. In his place Tywin was appointed as Hand of the King.

Stannis Baratheon, Robert’s brother,  knowing the truth about Cersei's children, had already closed Dragonstone to the world for a year, and ignored Ned Stark's calls for him to return to his duty as Master of Ships and return the royal fleet to the capital. All this time Dragonstone stayed hostile to everyone outside and took any ship that would come close to the island. Renly wedded the 14 years old girl Lady Margaery Tyrell and crowned himself as King of the Seven Kingdoms, followed by all the might of the Reach and the stormlands, ignoring the fact that Joffrey was officially the rightful king, and refusing to support his elder brother Stannis. During the war, Robb Stark, Ned’s heir, sought to become an independent monarch as Balon Greyjoy. Civil War broke and Tywin sent Tyrion as his Hand Representative to fix the mess created by Cersei and Joffrey. Tyrion and Cersei had clashing views yet Tyrion managed to outsmart her and took most of her power away.

Cersei had the City Watch of King's Landing killing every known bastard child of Robert Baratheon in King's Landing. This prevented any challenge against Joffrey and any possibility for Stannis to prove the true parentage of Cersei's children. The only acknowledged bastards of Robert now are Mya Stone and Edric Storm. It's unknown how many bastards of Robert might live in the Seven Kingdoms, among them only two in the books are met, Bella and Gendry, but nobody, including themselves, knows that their father was Robert.

King’s Landing and many other places in the realm are starving because of the war: Renly is blocking the supply of food on the roseroad to King's Landing, while the west has been completely blocked by Robb Stark, causing the capital to suffer starvation. Cersei fears that Renly or Stannis will soon attack the city. She made Janos Slynt a lord because she absolutely needed the gold cloaks on her side before Eddard could hand over the throne to Stannis Baratheon. King’s Landing is now full of tension and the peasants are massing at the city gates, to seek shelter and safety from the war infuriating in the realm, but Littlefinger has introduced a tax to enter the city. There are guards and sellswords everywhere, and Cersei has tripled the City Watch and has thousands of craftsmen working on the defenses, including the Alchemists' Guild which has pledged ten thousand jars of wildfire.

Later King’s Landing receives news of the brothers Renly and Stannis fighting each other at Storm's End, making Cersei and Tyrion happy. The two celebrate the fact that Stannis and Renly are most likely going to battle, so whoever loses it’s a victory for them. Tywin is also made aware of this at Harrenhal. The small council discusses Renly’s mysterious death and Joffrey is disappointed, as he desired to have Renly’s head on spike as a revenge for all the times Renly had made fun of him for years. Tyrion, who was hoping for the brothers to kill each others, knows that Stannis is behind the death of Renly, and now he has enough strength to strike against them. Ser Loras is heading to Bitterbridge for his sister Margaery, and the council take this as an opportunity to have the Tyrells and the Reach on their side. They plan to win Loras, who’s Mace Tyrell’s favorite son and Littlefinger heads to Bitterbridge to treat with the Tyrells. At the same time the Greyjoys officially enter the war and invade the North, raiding the coast, pillaging, and raping, angering Cersei who wished Robert would have killed all the ironmen, back during Greyjoy Rebellion.

King’s Landing falls into chaos as a result of Renly and Robb’s actions, that led the capital to starve. There’s hatred against King Joffrey, the Lannisters, and the High Septon, the latter is killed during a furious riot that occurs right after Princess Myrcella and Ser Arys Oakheart leave the city for Dorne. King’s Landing is now full of conspirators who plan to have the population and the sellswords fighting for Stannis Baratheon, when the time comes.

Everything went wrong for Tyrion when months later Stannis, after killing Renly and taking power in the stormlands as the one true king, laid siege to King's Landing and Lord Tywin returned with Lord Mace Tyrell and Lord Randyll Tarly to defeat him and claim his place as Hand of the King.

Later like Renly, Balon Greyjoy and Robb Stark where murdered and the only one to oppose the Lannisters rule was Stannis Baratheon who was still alive, hiding in Dragonstone. To stop the rebellion of the North, Lord Tywin had officially declared to have finally found Princess Arya Stark, and was taken in King's Landing by Bolton's men to be taken back to the North to marry Lord Ramsay Bolton, however, unknown to everyone, even the Boltons, the girls is a fraud and is actually Jeyne Poole, childhood friend of Sansa Stark, who had lived somewhere in King's Landing away from the Red Keep, all this time during the war. The Lannisters intended to forge an alliance with the Tyrells, one of the most powerful families on Westeros, by wedding Margaery Tyrell to King Joffrey I. This however failed when Margaery’s grandmother, Olenna Redwyne, concerned with Joffrey’s cruelty, poisoned Joffrey with the help of Littlefinger during their wedding feast. The blame however fell on Sansa Stark, who was being held as a hostage, and married to Tyrion Lannister. Tyrion was imprisoned yet Sansa disappeared.

During the war her brother Jaime was released from his imprisonment by Catelyn Tully and arrived to King's Landing to help her mourn their dead son (even though Jaime had no love for Joffrey). After Joffrey's death and with Mace's refusal to marry her with his son, Willas, Tywin had planned to sent Cersei back to Casterly Rock, so he could remain alone with King Tommen I. Tyrion was going to be executed yet he escaped with the help of Lord Varys and his brother and killed Lord Tywin for what he did to him and Tysha years ago, leaving Cersei with all the power.

Margaery married the new king Tommen who was just a child and had a sweeter nature than his brother and mother. The two won't consume their marriage until Tommen will come of age. Ser Loras becomes a genuine friend of Tommen, the big brother he never had. After the Blackwater Loras had replaced the deceased Mandon Moore as Kingsguard, and was now protecting Tommen and taking orders from Ser Jaime. Margaery gives Tommen a lot of cats. The Tyrells were actually trying to act as a true united family, but the paranoid Queen Dowager wanted to stop it at any cost.

Cersei's rule was short and disastrous: she took control over her son Tommen and resumed her position as Dowager Queen. With Tyrion being a criminal and an exiled kinslayer, Cersei is now Lady of Casterly Rock, officially acknowledged by her uncle Kevan. Cersei thought she could prove herself to be a better ruler than her father, however she proved herself to be wrong when she drives the realm in a complete chaotic state. Her pettiness, megalomania and easily wounded pride frequently lead her to make rash decisions, rarely considering what unintended consequences her actions might have. She lacks the patience for dealing with the tedious yet vital details of administration, and increasingly avoids facing unpleasant facts, surrounding herself with sycophants rather than honest and competent advisers.

She gained more weight and started to drink more and have sex with people, taking all of these habits from her dead husband King Robert. Her paranoia and hysteria increased, also leading her to have Lord Hellyne burning the Tower of the Hand with wildfire. The Queen was paranoid and obsessed with Stannis, Tyrion, and the Tyrells trying to take King's Landing. She had hallucinations and nightmares, seeing Eddard Stark, her father, Sansa Stark, and even Sansa's direwolf Lady. Cersei fills King Tommen's small council with cravens and lickspittles, her own agents who would be complete loyal to her: Lord Orton Merryweather as Master of Laws, Ser Harys Swyft (Lancel's maternal grandfather) as Hand, partially to use as a hostage against her uncle, Grand Maester Pycelle, Lord Gyles Rosby as Master of Coin and a former ally of Stannis Aurane Waters as Master of Ships, and the renegade former maester Qyburn as Master of Whisperers, the latter was given the permission to take young girls into his dungeon and torture them to death for his experiments, making Pycelle furious.

Cersei kept Tommen away from the small council and took the rule of the Seven Kingdoms for herself. Kevan Lannister is infuriated by this and after having a quarrel with his niece, he leaves King's Landing sometime later, with Tywin's body, to go with his son Lancel to Castle Darry and later to Casterly Rock. Kevan and Cersei always had a bad relationship, and Cersei always thought that Kevan disliked her because she's a woman, but Kevan had always found her unfit as a mother as well as a ruler. To spite her uncle, Cersei names Daven Lannister the new Warden of the West, while Damion Lannister is made castellan of Casterly Rock. Daven remained besieging Riverrun with Emmon Frey and Genna Lannister. As a challenge Kevan refused to serve Cersei as her puppet, and left her alone, surrounded by cravens, lackeys, fools, and enemies. Before leaving, Kevan told Jaime and Cersei that he always knew about their incestous relationship. Actually every Lannister, except Tywin, was always suspecting that. She befriends Lady Taena Merryweather, having her spying the Tyrells for her, and even forcing her to sex with her in the bed. She also kept going with her sexual relationships with the Kettleblack brothers, Osmund, Osfryd, and Osney.

A new rumor was spreading throughout the realm: Sandor Clegane had joined Beric Dondarrion outlaws. The Queen was made aware about the infamout Raid on Saltapans, where the outlaws have pillaged Saltpans and savagely raped and mutilated the townsmen. The reports mentioned that their leader was the Hound. In truth it is later revealed the rumour that it was Beric and Sandor's doing was made up by Randyll Tarly, as he plans to have all the realm against Lord Beric Dondarrion and help to finally have him captured. The one who truly led the brutal raid on Saltpans was the dangerous criminal named Rorge, who found the Hound's helmet and wore it. After alienating Kevan, Cersei sent her brother Jaime away, so he couldn't stop her plans. Jaime tried to reason with his sister and asked her to make peace with Kevan, but he only angered her.

Jaime is sent in the riverlands to help Daven and deal with Ser Brynden Tully in the Siege of Riverrun, help the Freys and the Lannister army with the river lords, and deal with the former Mountain's men in Harrenhal. Jaime went to the riverlands with his party, including his squire Josmyn Peckledon, Ser Ilyn Payne, the commander of the City Watch Ser Addam Marbrand, Ser Flement Brax, Ser Lyle Crakehall, Lord Ronnet Connington, and others. During his journey he develops empathy for the people of the riverlands, victim of the worst events of the war, and starts to reconsider his relationship with the hateful Cersei, believing she's been the main reason of his former villainous behavior.

Cersei has bounty hunters to search for Tyrion in all of Westeros and Essos and orders to bring her his head. At the same time she wanted to get rid of the Tyrell army and the Redwyne fleet, so she ordered Mace Tyrell to go with Mathis Rowan to Storm's End,  which is still held by Stannis' loyalist and take it in the name of King Tommen. While Paxter Redwyne has to go with his fleet to Dragonstone and take it, while Stannis was at the Wall with Lord Commander Jon Snow, his wife Selyse, and his daughter Shireen. Mace's second son, Garlan Tyrell also left the capital for Brightwater Keep, the seat of House Florent, officially rebels for being bannermen to Stannis Baratheon. The castle is held by Ser Colin Florent while Lord Alekyne Florent is in Oldtown, Axell and Selyse are with Stannis, and Erren Florent, Selyse's younger brother is held captive in Highgarden. Cersei thought that sending Mace and Paxter away  was a smart move: with Lady Olenna and Lady Alerie (Mace's wife), and Lady Leonette (Garlan's wife) gone, Margaery was left with only her female cousins and Ser Loras Tyrell, who stayed in King's Landing as a member of the Kingsguard. Cersei knew that  whoever was going to lose the battles she would have won: either the Tyrells and Lord Redwyne were going to die fighting the forces of King Stannis, or Stannis would be damaged anyway.

The Queen started a political campaign of intrigue to remove the Tyrells from the capital as she thought in her paranoia that they were trying to seize the throne for themselves, this because Qyburn found a Tyrell coin in the dungeon where Tyrion was being held (the coin was obviously put there by Lord Varys in order to create tension between Cersei and the Tyrells). Another such coin is found in the room of a Jailer who disappeared the same time as Tyrion (the Jailer is one of Varys' alias'). Cersei alienated Jaime and Kevan, the latter leaving King's Landing with Tywin's body for Darry and later Casterly Rock, angered by her. Meanwhile, Cersei's cousin Ser Daven Lannister was still besieging Riverrun with the Freys as Ser Brynden Tully was still holding the castle. The rest of the Lannister army was in the riverlands along with Randyll Tarly, trying to bring peace to the riverlords who had supported King Robb during the war. The Freys and the Lannisters still kept northern hostages such as Jon Umber, Harrion Karstark and Wylis Manderly, to force the North to be loyal to the Crown and it's new ruler Roose Bolton.

Cersei kept damaging Tywin's hard work to keep order in the Seven Kingdoms, having the High Septon murdered in his sleep by Ser Osney Kettleblack and refusing to honor the Crown's debts to the Iron Bank of Braavos and the Faith of the Seven, causing the Iron Bank to go in support of King Stannis Baratheon and the Faith to refuse to bless King Tommen I. This causes economic chaos in the realm. With the money owed, Cersei started to construct a new royal fleet of warships in command of Aurane Waters. The Queen also sends Ser Balon Swann to Dorne, to deal with Prince Doran Martell and bring him the head of Ser Gregor Clegane who had killed Prince Oberyn Martell, Elia Martell, and Aegon VI Targaryen, in order to have back in King's Landing her daughter Myrcella, away from the dangerous Sand Snakes and the half-mad Obara Sand. Not knowing that Doran had sent his older son Quentyn Martell to Meereen for a secret alliance with Daenerys, Cersei' s secret mission was to invite Prince Trystane to accompany his betrothed, then kill him along the way somewhere in the kingswood in a staged assault, for which Tyrion was supposed to be blamed, with Prince Doran preferably bearing witness to the fact that the attack is not the fault of the queen's men, but this failed as Doran was made aware of this and only let Myrcella go back to King's Landing.

Cersei organized other failed  plots such as having Bronn killed at Stokeworth by the husband of Falyse Stokeworth (Bronn killed him and had his men throw Falyse out of Stokeworth), and have Jon Snow, who was an ally to Stannis and the North, murdered at Castle Black (though he still got murdered, but not because of Cersei).

A letter arrived at King's Landing, informing Cersei that Lord  Davos Seaworth was taken captive by Wyman Manderly in White Harbor, which was controlled by Freys, and was going to be executed (later it's revealed that the one who's been killed was just a criminal and that Davos was sent by Lord Wyman Manderly to Skagos, to find Rickon Stark). At the same time the ironborn took advantage of the chaos and King Euron Greyjoy started to attack the Reach, while his brother Victarion Greyjoy was sent to Slaver's Bay to meet Queen Daenerys Targaryen. Cersei ignores the complaints of Loras, Margaery, and Willas Tyrell, Mace's firstborn son who was acting as Lord of Highgarden, and refused to send the Redwyne fleet back to the Reach to deal with ironmen, saying that they first have to deal with Stannis Baratheon, making the Tyrells more angry.

Later however Loras returned to beg Cersei to let the Redwyne fleet leave Dragonstone again, and Cersei refuses again but let him go to the infamous island, to help Lord Redwyne to deal with Stannis' garrison. Ser Rolland Storm held the castle and thanks to Ser Loras' rashness, the siege soon became a slaughter. About a thousand men died, mainly Tyrell men. Loras got heavily and seriously wounded, as Stannis' men poured boiling oil over him. Loras is reported to be ugly, ruined, and dying. Cersei didn't wait to tell Margaery everything with a malicious smile, even exaggerating the story, and leaving the little girl to her grief. While he was losing Dragonstone, King Stannis had taken Deepwood Motte from the ironborn, taking Princess Asha Greyjoy as his captive, and winning the support of many house of the North, including House Mormont, who had previously denied him in a letter. Stannis marched with his army of two different religions, but got stuck in the wolfswood in a snowstorm, while Roose Bolton has been preparing for the imminent siege, gathering the Freys and his disloyal bannermen in Winterfell, there also with him, Wyman Manderly, Ramsay Bolton, Jeyne "Arya", and Theon "Reek". Cersei hopes the Boltons will manage to capture or kill Stannis.

Jaime and most powerful men of the westerlands were still away, dealing with the chaos in the riverlands. With all of the surviving force of the Lannister army away in the riverlands, and the armies of the Reach dealing with Stannis, Euron Greyjoy and his ironborn, and the Florents, King's Landing was left only to the protection of the remaining men of the City Watch: here the Sparrows quickly started to spread in all the city (fled from the violence and rapes of holy women outside the capital) and preach the Faith of the Seven and publicly going against the corrupted greedy Faith in King's Landing. They are led by a men who is referred as the High Sparrow. Cersei didn't take the problem seriously and let them did what they wanted, even forcing the septons of the city to choose the High Sparrow as the new High Septon and trying to abolish all of the brothels from King's Landing, to protect the women and build a sense of morality in the city. The new High Septon manipulates Queen Cersei into overturning Jaehaery's law (Jaehaerys had the Faith agree to disband the Faith Militant) and the Faith Militant is born again. Cersei was really happy about it, because she thought she had solved the problem with the sparrows and that this was a huge strike against the heretic Stannis Baratheon.

The Faith Militant has two orders: the first one the Warrior' Sons, knights who have renounced their titles, lands, gold and possessions to fight for the Seven and the High Septon. They wear inlaid silver armor over hair shirts, rainbow cloaks, and swords with star-shaped crystals in their pommels. They developed a reputation for fanaticism and implacable hatred for enemies of the Faith. The second one the Poor Fellows, a more humble order for commoners and women. Acting as a militant counterpart to begging brothers, Poor Fellows wander the realm and escort pilgrims between septs. They are lightly-armed footmen, who carry whatever weapons they can make or find, often axes or cudgels, and wear star badges, red on white. Ser Lancel Lannister abandoned his wife at Darry without consummating his marriage, and joined the Warrior's Sons, making his father Kevan furious like Jaime did with Tywin.

When Lord Gyles Rosby died, Cersei accuses Grand Maester Pycelle of being responsible, which he objects to. She immediately dismisses the ward of Gyles Rosby as not of Gyles’s blood and contrives to seize Rosby’s gold, lands and castle due to the lack of a clear heir to the childless Lord Rosby. Pycelle begins to object, telling her again that Gyles had a ward, but she orders the hesitant Pycelle to tell the ward that Gyles’s dying wish was that all his lands and wealth go to King Tommen Baratheon, which is not true.

Instead of unifying the realm Cersei tried to undermine the Tyrells by claims against Margaery’s virginity and giving religion more power, the plan initially succeeded: Margaery was arrested for fornication along with her cousins Alla, Megga, and Elinor, with many nobles accused of having sexual relationships with them: Lord Paxter's twin sons, Osney Kettleblack, Horas and Hobber, Mark Mullendore, Jhalabar Xho, Hugh Clifton, Lambert Turnberry, Bayard Norcross, Hamish, Ser Tallad, and the Blue Bard. Cersei and Qyburn tortured the Blue Bard until he lost his mind and was forced to give the names of the men who had been arrested. Of course Ser Osney was part of Cersei's plot and was happy to be blamed and ready to give false testimony to the Faith Militant and blame Queen Margaery. Cersei's plan backfired when the High Sparrow took Ser Osney and the Blue Bard under his custody and had Osney tortured until he confessed Cersei's crime. Lancel also testifies against his cousin. Then all of Cersei' lovers were discovered. The Faith chased Cersei until the big woman, Septa Unella took her and imprisoned her.

Cersei and Margaery remained prisoners of the Faith. Meanwhile, Pycelle summoned Kevan Lannister to return to King's Landing as Lord Regent Protector of the Realm. The news of the arrest of Margaery Tyrell reached the ears of Lord Mace Tyrell, who left the siege at Storm's End to Lord Mathis Rowan and returned to King's Landing with an army. Randyll Tarly also arrived with his army, ready to deal with the Faith and highly disapproving what Cersei has done to realm. Cersei's agents Taena and Orton Merryweather fled back to the south to avoid the Faith and return to their child at Longtable, as well as Aurane Waters who left with his fleet for the Stepstones. Cersei is relieved to learn from Qyburn of the Merryweathers' departure, since Taena is privy to much incriminating information, which could be used against her by her accusers of the newly zealous and militant Faith. Cersei assumes she need not fear that her former bedmaid and confidant would betray her under interrogation or torture. Now Paxter Redwyne is the Master of Ships while Mace is Hand of the King, Randyll the Master of Laws, and Harys Swyft stayed as Master of Coin.

Kevan and Pycelle ignored Cersei and left her to her captivity, while Ser Osney Kettleblack is sentenced to death for the murder of the previous High Septon. As for Margaery, the High Sparrow admitted her case is weak, and that she's most likely going to be released. However, if found guilty Cersei will be executed in the name of the Gods. Desperate Cersei refuses to confess her crimes to the High Septon, who also wanted her to confess about her incestous relationships with Jaime and the fact that her children are all bastards of their relationship. She begs Qyburn to write to Jaime to return to King's Landing and fight for her. But Jaime, who had resolved the matters in Harrenhal, Riverrun (with Emmon frey ruling the castle, the Blackfish disappeared, Petyr Baelish Lord of the Trident, and Edmure Tully living now in Casterly Rock with Roslin Frey) and Raventree Hall, ignores her letter, furious about her infidelities with Lancel and the Kettleblacks. Instead her travels in the riverlands with Brienne of Tarth, who has failed to save Sansa and Arya yet.

Cersei eventually breaks and finally confesses to the High Septon, admitting it's all true except for her incestuous relationship with Jaime, wanting to protect Tommen and Myrcella from Stannis and the Faith at any cost. She accuses Stannis Baratheon of being a power hungry liar who would sacrifice his own family to get the Iron Throne. The High Septon was satisfied to hear this. He's more worried about Stannis, as he declared him as an heretic enemy of the realm and the Faith, who has abandoned the Seven to follow R'hllor the Red Demon. It was rumored that Stannis considered burning the Great Sept of Baelor for Melisandre. To get the real truth, though, the High Septon means to have her tried by the Faith or trial by combat, where Cersei would be represented by a knight of the Kingsguard. He is unsure of all the crimes she has committed so the only way to pick the truth from the false is to let the gods decide.

Cersei is allowed to visit Lord Regent Kevan, and she learns that Jaime has gone missing, the Golden Company has invaded the stormlands and that there's a war going on down there. Kevan thinks the sellswords are fighting for Stannis. Then he tells Cersei the bad news from Balon Swann: Myrcella lost an ear in Dorne, and Ser Arys Oakheart of the Kingsguard died. Qyburn however was ready to replace Ser Arys with his new member.

Cersei is forced to make the Walk of Atonement, commonly better known as "walk of shame" for the shouts of the word. She knew it was the only way to escape the Great Sept and return to the Red Keep and see the scared Tommen again before her possible imminent death. Meanwhile, Margaery has chosen to be judged by the Faith, since she has many friends who are going to defend her against Cersei's former accusations. But Cersei knew she does not have enough friends to risk that kind of trial. The septas arrived with a group of Silent Sisters, who stripped Cersei naked and shaved her of literally every hair on her body (not in the show for obvious reasons). Led by Ser Lancel and other men of an escort of Warrior's Sons, Cersei found herself in the same spot where Eddard Stark was executed, which it made her think about how Joffrey had ruined every chance of a good ending for her family, killing Ned Stark and causing the North to rebel, while removing every chance of making peace with them in order to have the freedom to deal with Stannis and Renly.

Cersei was forced to strip naked before the crowd and walk to the Red Keep. Initially she walked with dignity, ignoring the insults and worse (such as rotten vegetables and a cat carcass) the crowd thrown at her, but as the walk continued and the insults grown worse, mocking her faded beauty and the signs of age on her body, Cersei struggled to maintain her composure. As she walked, Cersei had hallucinations, seeing faces of others in the crowd; an angry Tywin frowning, Ned and Sansa Stark, along with Lady the direwolf staring accusingly at her, Tyrion laughing at her and finally, the face of Maggy the Frog intoning her prophecy: Queen you shall be, until there comes another, younger and more beautiful, to cast you down and take all you hold most dear. At this, Cersei breaks down in tears and runs for the Red Keep, collapsing as soon as she staggers into the courtyard. Kevan Lannister had not yet forgiven her for her actions bur ordered her covered up and removed, at which point Cersei is picked up by an eight-foot-tall giant. Qybrun was the only one nice to Cersei and he introduced the giant Kingsguard as Ser Robert Strong, much to her pleasure.

Cersei remained in the Red Keep as she's not allowed to go anywhere outside it, nor she dares to do it. She has now an absolute fear for the smallfolk of King's Landing and has gone quiet since her walk of shame. She stays with Tommen and waits for Myrcella to be back at home, as she has started to travel back to King's Landing while Prince Doran refused to let Trystane go with her and let him stay in Sunspear, the capital of Dorne. Kevan Lannister ruled as regent and he improved the relations with the Tyrells by naming Lord Mace Tyrell as Hand of the King. Randyll Tarly was disgusted by the men of Gregor Clegane, and suggested to let them take the Black "where such scum belongs", but Kevan doesn't allow this. While Ser Loras is dying of his wounds in Dragonstone, Lord Redwyne finally returns to the Reach, ready to help the lord and Willas Tyrell to fight against King Euron Greyjoy. Finally Kevan has learned that the responsible of the war in the stormlands is not Stannis Baratheon, but a Targaryen pretender leading the Golden Company with Lord Jon Connington, who was thought to be dead in Lys all these years.

Kevan finds himself in a difficult position as the Faith has completely taken control over King's Landing and with the Lannister army still in the riverlands, he's surrounded by the Tyrell army and can't openly oppose against the annoyed Mace and Randyll. Mace dismisses the three living kings in Westeros: he says that Paxter Redwyne will deal with Euron, Stannis will be killed by the Boltons, and that Jon Connington and the Golden Company are not a problem. Kevan however fears that Daenerys Targaryen might join the Golden Company from Meereen. He sends Ser Harys Swyft to Braavos with former Gregor's thug Raff the Sweetling and other guards to deal with the Iron Bank. Kevan's rule was short lived because he was murdered by Varys and his little birds, right after he revealed to him that the man leading the Golden Company is led by a boy who claims to be King Aegon VI Targaryen, who was thought to be killed as a baby by Ser Gregor. Varys apologized to him, explaining that he needs the realm to remain an chaotic state and that Kevan was doing too much of a good job at fixing it. Kevan's death will only add more tension between Cersei and the Tyrells. Finally winter comes: it's snowing in King's Landing. Cersei is going to be judged by the trial by combat with her champion being Ser Robert Strong. If she wins she will be sent back to Casterly Rock.

Destruction of the Great Sept of Baelor
During the sixth season of the TV series, Cersei was sure about her survival in the trial by combat with Ser Gregor at her side. However her plan is thwarted when King Tommen, manipulated by the High Septon, decides to abolish any form of trial by battle. This means Cersei has to face a real trial, with most of the nobility and the common folk against her. Having no other choice between losing his position or commit mass murder, Qyburn reveals to her that Varys' little birds confirmed the rumor of King Aerys' secret wildfire plot.

The day of the trials of Cersei and Ser Loras, the former queen regent remains at the Red Keep, while a lot of lords, ladies, and knights attend the trials at the Great Sept of Baelor. Among the attendants are Queen Margaery Tyrell, the Lord Regent and Hand of the King Ser Kevan Lannister, Lord Mace Tyrell, and Brother Lancel. Cersei has the Mountain prevent Tommen to attend the trial and remain in the Red Keep, while most of the Sparrows and the High Septon are in the Great Sept. Aerys's caches of wilfire are placed in the tunnels beneath the sept, and Cersei prepares to destroy the High Sparrow and defeat the Faith by destroying the Great Sept of Baelor. Three burning candles are placed in a pool of wildfire, the flames getting closer to the extremely flammable substance as the candles melt.

Loras' trial ends with the knight confessing his sins and joining with the military arm of the Faith, with the Sparrows. Noticing Cersei's absence, Margaery has figured out that Cersei's and Tommen's absences are a serious cause for concern and tries to leave the Sept, along with her brother, father, and the rest of the assembly, but the Sparrows prevent them from doing so, as the High Sparrow dismisses her concerns, and insists that the trial continues. Instead, he sends Brother Lancel to the Red Keep, but one of Qyburn's little birds stops him from leaving the Great Sept by baiting him to the crypts. At the same time, for an unknown reason, Qyburn murders Grand Maester Pycelle, making himself guilty of another crime to the Citadel and the Enclave of the Maesters.

In the tunnels, Lancel is injured by Qyburn's little bird and finds dozens of barrels of wildfire. The barrels explode, killing Lancel. Margaery and the High Sparrow look at each other for the last time before the fire punches through the seven-point star mosaic floor directly where the High Sparrow was standing, burning the flesh off his bones and killing him instantly. The force of the explosion destroys the statues of the Seven and flames spread throughout the interior, killing everyone inside and some outside as the building collapses. The elaborate windows explode outwards, and the ancient stonework shatters as the explosion peaks, the shockwave obliterating all structures within a mile of the Great Sept. A bell from one of the Sept's towers is flung into a building before crashing into the street below, killing a number of civilians. The flames spread out from the epicenter, incinerating everyone and everything in the surrounding area. As smoke and the screams of the terrified populace fill the air, Cersei looks on from her chamber in the Red Keep with great satisfaction, while Tommen, who was forced to remain in the Red Keep by Ser Gregor, watches on with shock and horror as the shattered remains of the once magnificent Sept crumble to the ground. Later Cersei has Septa Unella imprisoned with the only company of the Mountain for the rest of her life.

Somehow, the destruction of the Great Sept of Baelor does not seem to have serious consequences at all, besides simply making Cersei more disliked. Cersei insists that it was a tragic accident, but obviously no one, not even the smallfolk buys it. Her deeds caused the official extinction of House Baratheon, as its only legal member, King Tommen I, commits suicide immediately after witnessing the event. This results with Cersei usurping the Iron Throne thanks to her relation by marriage with Robert Baratheon. At the beginning, she has only the loyalty of the new Hand of the Queen Qyburn and the undead Ser Gregor Clegane. The Seven Kingdoms are divided and the Iron Throne power has little meaning, now ruled by House Lannister. Cersei rules the Crownlands, the Westerlands, the Riverlands, and the Stormlands, however none of these lands are truly loyal to her, though the westermen prefer their usual leaders over Daenerys Targaryen and her foreign army.

Cersei's actions caused damage to House Lannister, as one of its last smartest leaders, Kevan Lannister, died in the explosion and making Cersei a kinslayer with the deaths of her uncle and his son Lancel Lannister. Also the gravity of Cersei's actions fall especially on her heretic act against the mainstream religion of the realm: she destroyed an important historical monument, which was also the main holy house of the Faith of the Seven and seat of the High Septon. This puts the entire smallfolk, nobility, and houses of the Seven Kingdoms against her, and the loyalty of the Lannister army might be very low as well.

At first, Cersei had no allies or support: her actions caused a spiritual damage to her subjects; the westerlands were loyal to Ser Kevan, yet they remained loyal, along with Jaime, who is better liked by the westermen. The stormlands were deprived by Lord Tywin and Cersei from rebuild their military strength as they were only loyal to Stannis and Renly; the Reach, Dorne, the Iron Islands, the North, and the Vale are in rebellion and the Night's Watch is neutral; the river lords hate the Lannisters and the Freys and the Freys were known for supporting only the winners, so even with Lord Walder dead, the other Freys would have only supported the army with the greatest numbers. The positions of the Freys was seriously damaged by the murder of most (if not all) the sons of Lord Walder, leaving only females and likely the sons of Walder's sons to try to control their lands.

The deaths of Mace Tyrell and his children make Cersei guilty of the destruction of the main branch of House Tyrell. In the novels the Tyrells are a very fertile family and has a lot of male and female members. In the TV series, House Tyrell's status was uncertain, as it's never stated if there are other male Tyrells and only a few female cousins have been mentioned (according to season 3, Loras was the only male heir, though), however it seems the household is taking order from Lady Olenna Tyrell, who's a Redwyne by birth. Olenna decided to plot her revenge by siding with the dornishmen, led by Ellaria Sand, to support House Targaryen. This plan and their desire of vengeance backfired on both of them: Cersei forged an alliance with King Euron Greyjoy, who agreed to serve her as a lesser king, apparently in exchange of a marriage that would make him the Lord of the Seven Kingdoms. Euron destroyed Daenerys' fleet and defeated Dorne at sea, capturing Ellaria and the 3 eldest Sand Snakes for her, and his niece Yara for himself.

Cersei won to her side another powerful enemy: Lord Randyll Tarly, who was loyal to the Tyrells and is a proven battle commander. In fact, upon Daenerys Targaryen's invasion of the Seven Kingdoms, Randyll was convinced by Jaime to remain loyal to the crown and fight against House Tyrell. Cersei's worst problem is that the south is the most productive part of the realm: Highgarden and the Reach lords can simply cut the food supplies and block the roseroad, leading the crownlands to starvation and cause another riot in King's Landing. Despite all these points, somehow in the show, Highgarden is just easily taken by the army led by Jaime Lannister and Randyll Tarly. Highgarden was changed into a weaker castle, in contrast to its book counterpart, possibly to make somehow easier for the Lannisters to take it. Also, the lands of Highgarden are empty-looking, in contrast to their description in the books. Later, Daenerys retaliated by destroying the Lannister-Tarly host at the goldenroad.

In the show, Cersei's small council is unknown, if it still exists or it's just her, Qyburn, Euron, and Jaime making plans. Her novel counterpart had filled the council with sycophants, until the Faith arrested her and Qyburn became her only friend. The Faith of the Seven has been left powerless and its members don't have a leader and even their military force, the Faith Militant, is disbanded. The only Great Sept of the Seven now can be found in Oldtown, the Starry Sept, which used to be older seat of the High Septon before Aegon's Conquest, and the Faith might gather back their strength there, beyond the reach of the Queen. Regardless, it will remain unknown and irrelevant, as the TV series is going to its ending.

Novels and TV series
In the original novels, the fifth book ends with the arrival of winter: King Stannis Baratheon and the Boltons are still alive when winter comes and their battle starts during the very begin of the sixth book, while Lord Baelish plans to bring the army of the Vale with Sansa to Winterfell as well. Jon Snow is still at the Wall and Dorne, led by Prince Doran Martell who's still alive, is joining with the boy who claims to be Aegon Targaryen and is leading the Golden Company with his Hand of the King Jon Connington and took over the stormlands. The Second Siege of Meereen is still occurring with Ser Barristan Selmy alive and ruling Meereen for Daenerys, with the Iron Fleet being led by Victarion Greyjoy instead of Theon and Yara, who are Stannis' prisoners, and Victarion plans to betray Euron for Daenerys. At the same time, Euron is taking over the Reach with his fleet. The second phanse of the War of the Five Kings sees 4 kings: Tommen, Stannis, Euron, and Aegon. In the TV series the current monarchs are: Cersei, Euron and Daenerys. At the end of season 7, Jon abdicated his throne and swore allegiance to Daenerys.

With the novels and the TV series being 2 different stories now, it's yet unknown what will happen with the Iron Throne and the Faith and if the Great Sept of Baelor will be destroyed by Cersei. Cersei helped to restore the Faith Militant as she genuinely thought is was a smart move against King Stannis and his religion of R'hllor, while solving the problem with the Sparrows in the capital as well. Like in the show, there's a trial by combat between the Faith and the Iron Throne, with Ser Robert Strong as Cersei's champion, and Myrcella is on her way back to King's Landing with Nymeria Sand and Tyene Sand to join the court. The fifth book ends with Varys's sudden appearance in the Red Keep after he went missing for a long time. The realm is ruled by Kevan and the high lords of the Reach: Mace Tyrell, Randyll Tarly, and Paxter Redwyne. Lord Redwyne and Lord Mathis Rowan are out of the capital dealing with Euron's fleet at the Arbor and Stannis's forces at Storm's End.

Ser Loras Tyrell lies injured and reported dying of serious wounds at Dragonstone, after fighting against Stannis's forces. Varys and his little birds murder Kevan and Pycelle in the Grand Maester's rooms, with Varys aplogizing to Kevan and explaining his intentions of killing him for keeping the realm in a chaotic state and Kevan, being a smart and cautious man, was making too much of a good job at fixing Cersei's damage and making strong alliances and friends again. By killing Kevan, Varys makes sure this will draw Cersei crazier and he's sure she will blame House Tyrell for the assassination. Cersei lacks sycophants and friends as well: Lord Orton Merryweather and his wife Lady Taena fled the capital to avoid the Faith to return to Longtable; the Kettleblack brothers are not on her side anymore while Ser Osney Kettleblack is sentenced to death for the murder of Tyrion's High Septon; Aurane Waters betrayed Cersei after building a new fleet for her and stole it and went to the Stepstones. This only leaves Ser Harys Swyft, Lancel's maternal grandfather, who's at Braavos with the Mountain's men. Like in the show, Cersei's only allies are Qyburn and Ser Robert Strong.

Like in the show, Princess Myrcella is returning home, but Ellaria doesn't want her dead; instead Myrcella's threat in the novels is the traitor Ser Gerold Dayne the Darkstar, who wants her dead for an unknown reason.

This leaves King's Landing mainly under control of the High Septon, Mace Tyrell, and Randyll Tarly. The imposing Lord Tarly is considered the biggest threat to the Lannisters in the capital. Also the maesters of the Citadel are planning something enigmatic as well, as Archmaester Marwyn left Oldtown to meet Queen Daenerys at Meereen, like the High Priest of Volantis Benerro sent Moqorro to meet her. Without Pycelle the position of Grand Maester is vacant and might have murdered Pycelle because the Enclave was planning to name Maester Gormon as the new replacement for Pycelle, and Gormon is born a Tyrell, putting another member of the house in King's Landing. Myrcella might die before reaching King's Landing, and her death might be the last drop to cause Cersei's madness. If the Great Sept of Baelor will be destroyed by wildfire in the novels, Lord Tarly might survive the event by not attending the trial, however the show is telling its own story, as George R. R. Martin explained. For example, Jon Snow and Yara Greyjoy replaced Stannis and Victarion in season 6 with similar roles, so the future of the books remains unknown and unpredictable, with George changing things all the time.

Cersei's relationship with her brother Jaime went to an end in the fourth book. Cersei started alienating Jaime and Kevan after Tywin's death, causing the shock of the former and the anger of the latter. Cersei got rid of Jaime by sending him to the riverlands to deal with the Blackfish in the Second Siege of Riverrun, while Ser Balon Swann is the one who went to Dorne to deliver Ser Gregor's skull, take Myrcella, and deal with Ser Gerold Dayne. During his travel in the riverlands, Jaime went to Castle Darry to meet Kevan and Lord Lancel Lannister, head of House Lannister of Darry since the end of the Red Wedding. It's from Lancel that Jaime learns about Cersei's infidelities with Lancel, while she also has sex with the 3 Kettleblack brothers and Lady Taena Merryweather. This caused Jaime's anger and while watching the situation in the riverlands, he realized that his relation with Cersei is poison: it's what kills Jaime's better human part and makes Jaime a puppet under control of the Queen. Jaime reminded how he would have killed Arya, back when the direwolf Nymeria hurt Joffrey, hadn't Jory Cassel found first, and thinks how Cersei is the main reason of his worst crimes and deeds. He gave up his honor and conscience for her, and in turn she didn't even cared and had sex with many other men while he remained faithful to her. Jaime abandoned Cersei and ignored her answer to come as her champion against the Faith; instead he disappeared with Brienne of Tarth in a search to find Sandor Clegane and Sansa Stark.

At this point Cersei knows her children are doomed, as the witch Maggy predicted the deaths of Joffrey, Myrcella, and Tommen. Maggy's prophecy also talks about a new queen, far more young and beautiful than her. Cersei thinks it's Queen Margaery, who's currently 15/16 in the novels. However, in the TV series Queen Daenerys has finally left the Bay of Dragons (Slaver's Bay) after the Second Siege of Meereen, and landed to Westeros. In the books Dany meets the requirement of being far more young, since she's currently 15 in the novels, and Cersei might kill Margaery and believe she got rid of her threat, until Dany will arrive. The prophecy is the reason why Cersei hates Sansa and Margaery so much. Maggy however says that Cersei's true demise will be the "little brother" who will come to end her life. Cersei always thought it would be Tyrion, but the candidates are/were also Jaime, Sandor, Stannis, Euron, and Renly, the latter for Cersei's perspective, as the readers weren't aware of the prophecy at the time of the second book. The reason Cersei is so terrified of Tyrion, Stannis and Renly is because they are both "little brothers". However, a plot twist might see Cersei being killed by "little brothers" Jaime, Sandor, or even Euron.

In Season 8, Cersei, knowing Daenerys Targaryen’s reliance on her dragons, ordered Euron Greyjoy’s fleet to launch a surprise attack on her forces, leading to the death of Rhaegal and the capture and execution of Missandei. By killing the latter in front of Daenerys, she hopes to break her into the very thing she swore not to become in order to demonize her and justify her rule.

A short time later Daenerys and her allies attacked King's Landing. Riding Drogon she made short work of the Iron Fleet, the Golden Company, and Qyburn's scorpions and breached the wall so her forces could enter. The Lannister forces surrendered however Daenerys succumbed to the Targaryen Madness and had Drogon attack the city, killing soldier and innocent civilian alike. Despite the efforts of Jon Snow to stop the attack the Unsullied, Dokrathi and the Northerners eagerly joined in the attack.

Realizing that the city was lost, Cersei accompanied Qyburn and her Queensguard out of the castle. Ser Gregor protected them from falling debris before Sandor Clegane arrived to confront them. Gregor's hatred of his brother overrode the control Cersei and Qyburn had over him, and Gregor smashed Qyburn's head against a rock when he ordered Gregor to protect his queen. While the two brothers engaged in combat Cersei continued on and found Jaime in the maproom.

Jaime guided her into the Red Keep's crypt, but the escape route to the boat that would take them out of the city was blocked. With the crypt collapsing around them Jaime and Cersei professed their love for each other before they were crushed by the collapsing building, killing both of them. This finally ending the madness of Cersei Lannister and avenging all who were killed because of her actions, including Margaery Tyrell, Olenna Tyrell, Loras Tyrell, Kevan Lannister, Lancel Lannister, the High Sparrow, Tommen Baratheon, Ellaria Sand and the Sand Snakes, Grand Maester Pycelle and all the people who died in the destruction of the Great Sept of Baelor. Also that she indirectly was the cause of Ned Stark's execution and was behind the death of her late husband Robert Baratheon, finally avenging them as well.

With their children all dead, the deaths of Cersei and Jaime left Tyrion as the last surviving Lannister, and presumably Lord of House Lannister and heir to Casterly Rock.