He's the textbook 3edgy5u when it comes to duty, loyalty, etc. I remember seeing a comment once describing his work as the anti-Romance of the Three Kingdoms, a story primarily concerned with the three brothers of the Peach Garden Oath and their unbreakable bonds of honor and loyalty.
Hell, look at the supposed main source of inspiration behind the War of the Five Kings and the Stark-Lannister conflict in general which was central to the first three books, the War of the Roses. There was a guy who changed sides so frequently (and all too often hedged his bets, ie. parking his contingent far away from battles and jumping in only after one side started clearly winning, when he wasn't actively backstabbing his current overlord) in that conflict that he was literally nicknamed the 'Prince of Turncoats',
Baron John Wenlock, and
his story ended with
his irate ally galloping up to him & splitting his head open with an ax after attempting a backstab for the umpteenth time.
But in Gurm's work, someone like Wenlock would probably end up becoming king. There are entire houses that seem to just skate by with no meaningful or lasting consequences after betraying their oath over & over again, sometimes across millennia! The Boltons (multiple anti-Stark revolts, flayed a Stark king at one point, and yet
somehow they survive thousands of years into the story's present day even when their collaborators in one such rising, House Greystark, was annihilated) and Freys (showed up conveniently late to the climactic battle of Robert's Rebellion and got away with a lousy nickname, then threatened to not join his overlord in supporting the Starks at the start of the War of the Five Kings and got
rewarded for such insolence with the fatal marriage contract between Robb & one of his daughters) are the most infamous but far from the only ones like this.
The Peakes for example are literally only ever brought up when causing a civil war, a rebellion, or at the very least scheming against their own allies, and yet somehow like the Boltons, they too are still around in the time of the main story.
Realistically, a house with such a consistent record of backstabbing like the Boltons or Peakes would have been exterminated and their lands chopped up between more loyal nobles ages ago (especially the former, the early Stark kings were described in worldbuilding materials like
World of Ice and Fire as not being as honorable as Ned and actually quite ruthless & bloodthirsty, so it's especially wacky that they let the Boltons live for so long). Walder Frey would've at minimum been dispossessed of the Twins after Robert's Rebellion (because even if the Tullys/King Robert were inclined to let him live, no sane person would trust a man who's betrayed them once with a crossing of great strategic import), and so on.
Was medieval times that full of plots? I can understand some minor plotting by nobles, maybe a big plot by someone who got shafted hard by inheritance. But GoT has pretty much every person in very good stable position take massive risks for what amounts to a slight improvement in quality of life. Like what's the point in being a king compared to a major noble? It's not safer, you aren't eating better or have more free time. You aren't even that much in control.
Mass scheming & betrayal was more of a thing in the Late Middle Ages when the social contract was fraying under the stress of things like the Black Death and the Western Schism, and even then only in times of civil war (like the War of the Roses). In the context of the WOTR that Martin's war is based on though, it's worth noting that pretty much
NONE of the betrayals in that particular clusterfuck ended well. Building on the example of Wenlock above,
the Duke of Clarence also changed sides twice and while forgiven at first by his brother King Edward IV, was drowned in his favorite wine by said brother's order after planning another betrayal. Clarence's father-in-law,
Warwick the Kingmaker - the greatest single landowner in all of England at the time - was killed at Barnet for also betraying Edward IV and his massive estates split up between Edward's brothers, both of whom had married his daughters. And of course Clarence's brother Richard of Gloucester, AKA the (in)famous Richard III, was himself abandoned to his death at Bosworth Field by the Percies after betraying E4's memory by usurping his son Edward V (though Ricardians will in turn argue that he only did that because the boy-king's maternal family, the Woodvilles - themselves early defectors from Lancaster - were trying to betray him first).
Generally speaking, spitting on honor and being a backstabbing asshole in an attempt to get ahead was not a good idea in a society that depended hugely on honor (as a marker of how reliable you were personally) to function. Conversely, playing by the rules worked out pretty well more often than you might think based on GRRM's works. One of the biggest beneficiaries of Henry Tudor's ultimate victory was
the Earl of Oxford, a zealous Lancastrian loyalist from start to finish who never once forsook his allegiance despite spending a decade in a Yorkist prison, not even after it seemed that the Lancastrian cause had been completely destroyed with both the main Lancaster branch and its cadet dynasty the Beauforts at Tewkesbury. You can also compare the War of the Roses to an earlier, High Medieval civil conflict in the same kingdom,
'The Anarchy' of the 12th century: there weren't too many dramatic defections in that one and at one point the king of one side, Stephen of Blois, was actually captured by his enemies - but his enemies didn't kill him (as GRRM logic would dictate, imagine if the Lannisters had captured Robb or the Starks had Tywin & Joffrey at their mercy) because honor, which eventually saved their own marshal the Earl of Gloucester's life a year later as Stephen was exchanged for him after his capture.
