About me: Tywin is the head of House Lannister, Lord of Casterly Rock, Shield of Lannisport, and Warden of the West. Despite the several recent Kings in King's Landing, Tywin was the real power in King's Landing. Tywin was among the richest and most powerful people in Westeros. He is a widower with three children, Jaime, Cersei, and Tyrion. Casterly Rock, the Lannisters' ancestral seat of power, is located over a group of highly productive goldmines, which have provided the Lannisters with immense wealth and power over the years.
Tywin is the beloved son of Tytos Lannister. His father presided over a period of decline for the house, frittering away much of their fortune on poor investments and allowing himself to be mocked at court, creating a perception of weakness. Their vassals House Reyne of Castamere rebelled against Lord Tytos, and Tywin put down the rebellion personally, extinguishing their house and re-establishing the fearsome reputation of House Lannister. His ruthless destruction of House Reyne was immortalized in the song The Rains of Castamere and gave darker meaning to the common phrase "A Lannister always pays his debts," which originally referred solely to the Lannisters' vast fortune.
Tywin married his cousin Joanna Lannister and their first children were the fraternal twins Cersei and Jaime. She died after giving birth to Tyrion, which Tywin has blamed his son for ever since. When Jaime was diagnosed with a learning difficulty by a maester who predicted that he would never read, Tywin sat with his son for four hours a day until he overcame his problems with transposing letters in his mind, much to Jaime's resentment. Tywin despises his younger son, seeing him as misshapen and perverse. When Tyrion was very young, Jaime set him up with a whore. Jaime posed her as a common girl in distress that they rescued from bandits. Jaime chased the bandits off while Tyrion comforted the girl. They married, but when Tywin found out he was furious and made Jaime reveal the truth. Tywin paid her for every one of his guards to have sex with her and forced Tyrion to watch. Tyrion's hatred of Tywin has been reciprocated since. Nevertheless, all of Tywin's children are in awe of him and heed his counsel. He also took part in the War of the Ninepenny Kings.
A highly capable administrator, Tywin served as Hand of the King to Aerys II Targaryen for twenty years until the Mad King, driven by envy and distrust, rejected Tywin's proposal to marry his daughter Cersei to Prince Rhaegar and made his son Jaime a member of the Kingsguard. As members of the Kingsguard are forbidden to marry, Aerys had effectively robbed Tywin of his heir, which Tywin perceived as a great insult and resigned. During Robert's Rebellion Tywin remained neutral, answering neither the summons of the King nor the calls from the rebels, until the Battle of the Trident, after which it became clear that the rebels would win. Tywin marched with the full power of Casterly Rock to the capital, feigning that he had come to defend it from the rebellion. Aerys' advisors urged the King not to trust Tywin, even Jaime Lannister, who knew his father would never back the losing side in a war.
Nevertheless, on Pycelle's advice, the gates were opened to the massive Lannister army of 10 000 soldiers and began killing hundreds, even thousands of people. Tywin and his army ordered the city to be taken and the royal family murdered in a ruthless and efficient manner; as a result the city was sacked and the royal family massacred by Ser Gregor Clegane. Upon seeing Tywin's betrayal, Aerys ordered Jaime to bring him Tywin's head and instructed his royal pyromancer, Rossart, to set King's Landing ablaze. Jaime responded by personally stabbing the Mad King in the back, then slitting his throat. When Robert Baratheon and Eddard Stark reached the Red Keep, Tywin presented the bodies of the royal family as proof of his allegiance. After the rebellion, Robert Baratheon took the throne and married Tywin's daughter Cersei to cement the alliance between their houses.
Cersei gave birth to three children: Joffrey, Myrcella, and Tommen Baratheon. Unbeknownst to Tywin, all three children are the product of her incestuous relationship with Jaime. This was discovered by both Jon Arryn and Eddard Stark, albeit independently, and meant that Joffrey—the oldest of the Baratheon children and the heir apparent to the Iron Throne—had no actual claim to the throne. Tywin is close to his younger brother, Kevan, who is his chief advisor. Kevan's son Lancel was King Robert's squire; many secretly believe Lancel gave Robert too much wine during his fatal hunt on Cersei's orders.