Once upon a time, House Lannister was the most powerful House in Westeros. They have more money than the Seven Gods, but being stupid rich isn't enough to put your bloodline on the Iron Throne. Ruthless to a fault, House Lannister has a long, bloody history of being brutal to their enemies, and even worse to their friends.
In Game of Thrones, each member of House Lannister is a piece of work in their own twisted, sociopathic way. Other than snoozers Myrcella and Tommen, Tyrion seems to be the only Lannister with a working soul, and he's the black sheep of a family. So how did the Lannisters succeed in their reign of terror for so long? Here is Game of Thrones: 10 Rules That Members Of The Lannister Family Have To Follow.
Keep up appearances
The Lannisters may be a pack of monsters, but they can't just go around letting their horns show. Playing the game of thrones means they at least have to look like they care about the fate of the Seven Kingdoms, not just about ruling it.
Their personal lives also have to be pristine, though any insider knows the Lannisters are anything but. Cersei and Jaime manage to keep their incestuous affair under wraps for years. However, they don't count on how boring it is in the North and that kids have to make their own fun. Hence, Bran climbs the castle walls, witnesses the twins in the act, and Jaime is forced to shove him out the window. Jaime famously says, "The things I do for love," but it'd be more accurate to say, "The things I do for appearances."
Always hurt the ones you "love"
When it comes to weakness, the Lannister family has a zero tolerance policy. Tytos Lannister, Tywin's father, was the laughingstock of Casterly Rock, as he was perceived to be a weak leader. Before his death, Tywin was the Lannister patriarch, determined to stamp any softness out of his offspring. Of all his children, Twyin set his sights on Tyrion, who's already considered to be the bane of the Lannister name.
In his youth, Tyrion falls in love with a prostitute and marries her. This doesn't sit well with Tywin, so he teaches his son a lesson by siccing his guards on the girl and forcing Tyrion to watch. Tywin also turns Shae, another great love of Tyrion's, against him. Whoever said "home is where the heart is" never met the Lannisters.
Show them the money
Money and power don't necessarily go hand in hand, but most people don't know that. The Lannisters constantly flaunt their wealth to ensure status—and because it's fun to lord it over everyone. In his Kingsguard days, rather than wear traditional white armor, Jaime opts for gold. It's a true reflection of his family's affluence and ostentatiousness.
As extravagant as they are, the Lannisters are by and large smart with their money. Robert Baratheon, however, was not. Upon his death and the Lannisters gaining control of the Iron Throne, they find it very much in the red. Still, wealth must be shown off no matter what. Lady Olenna Tyrell is easily able to ensure an opulent affair for Joffrey and Margaery's wedding, playing on the Lannisters' need to flex their money muscles for all the world to see.
Father knows best
Cersei may sit atop the Iron Throne, but in the Lannister family, Tywin is King. Given the Lannisters' power, it's cruelly ironic that the adult children find themselves beholden to their daddy, particularly in matters of matrimony. Tywin would never be so base as to take his children's hearts into concern. Like anything else, marriage is a power play.
Tired of his children's sexual shenanigans, Tywin informs Tyrion that he will marry the young Sansa Stark. Tyrion protests, citing Sansa's young age, but Tywin wants to secure the North and get Tyrion out of his hair. This accomplishes both in one fell swoop. As for Cersei, Tywin matches her up with Ser Loras Tyrell. This means a Lannister stronghold on the Reach and an end to the rumors about Cersei and Jaime. Everybody wins. Well actually, Tywin wins. As long as he breathes, that's all that matters.
Be a lyin' lion
Honor is nothing but a surefire way to get yourself killed. Just ask Ned Stark's decapitated corpse. It's so much easier making deals and alliances when you have a fail-safe plan of going back on your word. When Daenerys Targaryen and Jon Snow appeal to Cersei for Lannister troops to battle the White Walkers, she hesitates but agrees. Later, she reveals to Jaime she has no intention of supplying a single man. Her enemies' armies can get themselves killed and hers will pick off the survivors. In retrospect, she maybe should have thought that one over.
Jaime, new to the honor game, is disgusted by Cersei. He abandons her to go fight in the North, amorously celebrating his victory with Brienne. But whether lying to her the whole time or lying to himself, Jaime betrays her by going back to Cersei. The smartest lions always cross their fingers behind their backs.
The truth will be what you make it
Telling lies is one thing. Repurposing the truth is a whole other barrel of snakes; one that can only be charmed by a House as powerful as Lannister. Jaime, for example, was a member of King Aerys' Kingsguard and he broke his oath by killing the ruler he was sworn to protect. Some view Jaime as a monstrous Kingslayer, but others, like King Robert, see him as a hero. Due to his influence, Jaime even got a promotion as Commander of the Kingsguard.
Also, notice how anyone close to sniffing out the truth about Joffrey's parentage ends up dead? First Jon Arryn and then Ned Stark. If there's nobody to refute that Joffrey and his siblings are the true heirs to the throne, then it must be true. If you prefer your head attached to your body, best believe the Lannisters.
Everyone who isn't us is an enemy
How did the Lannisters hold the Iron Throne for as long as they did? They made smart alliances but ultimately only trusted each other. Cersei gives this piece of advice to Joffrey. But she also tells him to be smart. If the Lannisters were to parade around declaring everyone an enemy, they wouldn't have many allies.
Cersei plays nice with the Starks until she no longer needs them. Same with the Tyrells. Deep down, Cersei hates them all, especially the sugar-sweet phony Margaery. These former allies of the Lannisters all have a tendency to die in a rather gruesome fashion. If only they knew what they really were all along—Lannister enemies.
Loyalty is for the weak
If everyone not bearing the name Lannister is disposable, surely this Great House must have some loyalty for each other, right? Please. If you believe that, you're as green as summer grass. Look what happened to the mighty Tywin. Here he is strutting around, thinking he's cock of the walk. But in the end, he dies on the toilet at the hands of Tyrion. This is a rare act of betrayal, but Tyrion was about to fry for Joffrey's murder. Besides, Tywin is an evil jerky jerk who had it coming.
But this still speaks to the fact that the Lannisters don't really give a hoot about each other. After Tywin meets the wrong end of Tyrion's crossbow, Tyrion takes off. Cersei, enraged, puts a price on Tyrion's head. The expression really should be, "Everyone who isn't me is an enemy."
Hear me roar!
This Lannister House motto is an apt one. That family does nothing quietly. Rather then send Ned Stark off to the Night's Watch, Joffrey orders his public execution. It's his first act as King, and it sure is a loud one.
In the Battle of the Blackwater, it's Cersei's idea to use wildfire against the enemies. This proves to be instrumental in the Lannisters' victory. She sure is a fan of the substance. Cersei uses the wildfire again, this time to blow up the Sept of Baelor and with it, her enemies, including Margaery and the High Sparrow. Nothing says "roar" like green, deadly fire.
A Lannister always pays his debts
Wait a minute. Paying your debts sounds like a very honest, honorable, and decidedly un-Lannister thing to do. How is this the Houses's unofficial motto? Simply put, the expression is a euphemism for seeking revenge. The notorious "Rains of Castamere" song is a tribute to Tywin's swift dispatching of House Castamere, who deigned to defy the Lannisters.
Tywin may consider Cersei an overall disappointment, but she sure knows how to pay her debts as well. Her lowest point of the entire series is when she's forced to take a Walk of Atonement as punishment for her crimes of morality. As Cersei walks the streets naked and humiliated, Septa Unella walks behind her, chanting "shame". But Cersei finds her vengeance. Once back in power, Cersei has the septa imprisoned and tortured. Septa Unella clearly didn't know who she was messing with. Shame.