GRRM has to be given credit, he’s created one of the most detailed fictional universes that there is, the Game of Thrones’ characters don’t just have a present they have a past that could make a spin-off series by itself. Character traits are determined by house words in more than one way. “A Lannister always pays his debts.” were not the initial Lannister house words ( those were ‘hear me roar’) but they became so in line with it that the whole of Westeros knows the Lannisters better owe them something good. However as shown below they aren’t the only ones who live up to their words.
House Tyrell: Growing Strong. This house has been growing with each series, slowly and cautiously like a wall-vine whose roots bore into the foundation until it breaks the wall. Margery Tyrell has lost three husbands the first was Renly Baratheon, Lord of Storms End, she then became queen marrying Joffrey and now has a much better king in Tommen Baratheon, although I doubt she could have been sent to prison under Joffrey’s watch, the torture rack maybe. Meanwhile her father, Mace Tyrell, now sits on the small council as the Master of Ship and Master of Coin. Growing strong is exactly what they are doing.
House Greyjoy: We do not sow. The Greyjoys are from the Iron Islands and as such don’t have any arable land to farm on. What they have succeeded in is raiding other places and that’s got them to the top of the food chain. They take what they want to take without shame. Even their position as rulers of the Iron Islands didn’t come out of work.
House Baratheon: Ours is the fury. The fury of Robert Baratheon is what ended the Targaryen’s rule. You do not steal a Baratheon’s betrothed. The fury of the Baratheons only stops when they are dead.
House Martell: Unbowed, unbent, unbroken. House Martell is the only house that managed to rejoin the seven kingdoms on its own terms. When Aegon Targaryen started conquering the place they were the only ones to successfully fend him off. Prince Oberyn himself demonstrates this trait, refusing to let the death of his sister get swept under the rug until his own death.
House Bolton: Our blades are sharp. The Bolton’s live up to their words like no other. They have a reputation for flaying people and it’s even on their banner. Ramsay Bolton’s maiming of Theon Greyjoy is where the Hannibal Lecter gene must have started. This family isn’t squeamish around blood. As the new rulers of Winterfell they made short work of Stanis and if Sansa knows what’s good for her she will stay hidden from Ramsay.
House Frey: House Frey is the only house that lacks words and this may be an indication that their words mean nothing. The double cross they pulled on Robb Stark was unforgivable even by GoT standards. Guest protection is an important part of Westeros culture making what they did a major taboo. They might have gained the Lannisters’ approval but at the cost of whatever little good reputation they had left if they had any to begin with.
House Stark: Winter is coming. This had to be left for last because there’s so much that could be interpreted from it. It could just mean that Winterfell shouldn’t be underestimated or it could foreshadow the return of the Starks. So far things look bleak for them with the remaining house members being scattered, some disemboweled and some blinded but there’s still some hope. GRRM is not one to let a characters death be vague and we’ve already discussed why Jon Snow could return and nothing would look better than him smiting down a hot blooded Targaryen while informing her that winter is finally here.