The richest house in Westeros. They control the Westerlands, and their primary branch is seated at Casterly Rock. The Lannisters are powerful and controlling, and completely merciless to those they view as weak. They are effectively the royal house and become the nemesis of the Starks early on. Their words are "Hear me Roar", but they also have a second, unofficial motto—"A Lannister always pays his debts"—which is an invitation to good Samaritans and a warning to bad ones. Their members are beautiful, with green eyes and blonde hair, and their sigil is a golden lion.
Lann the Clever and the Coming of the Andals
The Lannister bloodline would be founded by Lann the Clever, a trickster who only used his wits to tricked the Casterly dynasty out of Casterly Rock and founding his own royal line. A cadet branch would be founded in the city of Lannisport, and the heads of the Lannister family would reign as Kings of the Rock.
When the Andals invaded Westeros, King Tybolt Lannister would initially fight any Andal who entered his domain,
When King Robert visits his old friend Eddard to offer him the position of Hand of the King, the Lannisters are suspected to have killed the previous Hand, Jon Arryn, and attempting to kill the young Bran Stark. Only the latter is true, for Bran had witnessed Cersei and Jaime's affair while Arryn was murdered by his wife.
Lady Catelyn captures Tyrion Lannister at a crossroads inn to bring him to trial, prompting Lord Lannister to send raiders to Tully lands in an attempt to draw Lord Stark into the field, hoping to capture him for an exchange. Eddard, however, is waylaid on the streets of King's Landing by Ser Jaime and is injured in the melee, sending other men in his stead.
Tyrion escapes of his own volition, but the war continues along with intrigue in the capital, where Cersei has Eddard arrested. Tywin and Jaime win several victories over the riverlords, but the Tullys are soon joined by Eddard's son Robb and a host of northmen. Tywin repels one Stark army under Lord Roose Bolton in the Battle of the Green Fork, but this force turns out to have been a feint: with Tywin distracted, Robb captures Jaime in a surprise attack, and breaks his siege of Riverrun.
Meanwhile Cersei fears for her children if Stark informs Robert of her childrens' parentage. She has her cousin Lancel Lannister, Robert's squire, supply the king with strongwine during a boar hunt, resulting in Robert receiving a mortal wound. Soon her and Jaime's son Joffrey has become king, and orders the execution of Lord Stark, ruining any chance of peace. Jaime, despite his absence, is named Lord Commander of the Kingsguard. Tywin, having been named Hand, sends Tyrion to take up his duties while he campaigns in the Riverlands. Meanwhile Robert's brothers Stannis and Renly Baratheon have each contested Joffrey's right to the Iron Throne, while Robb Stark was declared King in the North by his bannermen. So begins the War of the Five Kings.
Tyrion is forbidden from taking Shae, his prostitute concubine with him, but Tyrion defies him anyway, while Cersei begins another incestuous relationship with her cousin, Lancel. Tywin moves his forces to Harrenhal to prevent being trapped by his opposition.