(Warning: The following contains potential SPOILERS for Game of Thrones season seven, as well as some discussion of the events of the recently concluded sixth season of the show. Proceed with whatever level of caution your friendly neighborhood Three-Eyed Raven suggests to you is wise...)
Now, here's the thing about Game of Thrones' Sandor 'The Hound' Clegane: Love him or hate him, he's probably not the first guy you'd think of as a natural lord. Sure, he'll kill some folks for you, no problem - and if you need unswerving loyalty to a horrifying cause, he's your guy (until he isn't of course, but more on that later). Noble, thoughtful lordship, though? That's very much not The Hound's thing. Which, of course, isn't too much of a problem, seeing as he's currently about as far from a lordship as it's possible to be - what with him being both a sworn enemy of the crown, and supposedly dead.
As it turns out, though:
The Hound's Family History Is Hiding An Important Game of Thrones Secret
One which, as it happens, may just have a huge impact on the next few seasons of the show. Y'see, Sandor Clegane didn't have what you would call a 'good' childhood. Along with most likely being set on fire by his own elder brother (Gregor 'The Mountain' Clegane), he also lived to see both the death of his sister in 'unusual circumstances' and, just after Robert Baratheon's ascension to the throne, his father's death in a hunting accident.
In other words? There's a distinct suspicion that The Mountain killed both his own sister and father, in order to give himself both the lordship of House Clegane, and free rein to commit whatever atrocities he so wished. Those same atrocities soon forced Sandor to depart, too - joining up with House Lannister, and refusing to take the vows of a knight, for fear of being seen as following in his brother's monstrous footsteps.
Which, y'know, didn't really work out all that well, what with The Hound eventually betraying the Lannisters, and departing for a life of running the hell away from the hideousness of Westeros - a life once thought cut short by Brienne of Tarth, but recently revealed to be continuing in mysterious fashion.
His brother Gregor, meanwhile, has managed to become even more monstrous - with his 'death' at the hands of Oberyn Martell leading to his apparent transformation into the zombie-like Ser Robert Strong, and a whole lot of horrifying torture and sexual assault on Cersei's behalf.
The reason that all matters, though?
As Far As Westeros Is Concerned, The Clegane Line Has Now Died Out
Y'see, with Gregor - or a series of mysterious accidents - having eliminated the rest of the Clegane family, and neither he nor Sandor having a known heir, the brothers' respective 'deaths' will have surely left their house in the hands of...well, someone else entirely.
Which, with the Clegane's being some of the more prominent bannermen of House Lannister, probably means that Cersei has cunningly failed to replace them at all, and is instead using their revenues to prop up her family's own dwindling resources.
Which might just prove to matter for one very big reason:
Sandor Clegane Isn't Actually Dead, And He Might Just Be About To Pick The Right Side For Once
Specifically, the last we saw of The Hound, he looked set to either head north with the Brotherhood Without Banners, looking to serve the interests of the Starks, or to ignore their offer, and seek vengeance on his brother and the Lannisters.
Now, whichever way the Hound ultimately opts to go, it looks set to open up the possibility of him ending the war in the good graces of any non-Lannister who might take charge of the realm - especially if that's any combination of the Lannister-loathing Jon Snow, Sansa Stark or Daenerys Targaryen. Which in turn might just mean that we see Sandor Clegane end the series not as an outlaw - but as the knighted lord of House Clegane.
That, though, isn't all. Y'see...
There's A Pretty Solid Chance That House Lannister Won't Survive The Arrival Of The New Order
Now, sure, Tyrion Lannister may well be a certain Khaleesi's favorite new advisor, but there's still the small matter of a whole lot of kinslaying (both real and perceived) to deal with once he returns to Westeros - not to mention the fact that the entire kingdom believes him to be a miniature monster.
In other words, there's a pretty good chance that Tyrion's only way of sticking around with his head on his shoulders - even if Daenerys were to become queen - would be to renounce his family name, and become either a Maester or a member of the Night's Watch. After all, if he were to essentially cease to be a Lannister, then the whole 'murdered his father and possibly his nephew, the King, and then ran away while his sister blew up half of King's Landing and doinked their other brother' thing might prove a little less terminal. What's more, it might even offer a way to avoid paying back the vast sums of money the Lannisters likely owe the Iron Bank of Braavos at this point.
Were that to be the case, though, then it would seem entirely within reason that House Lannister - much like House Targaryen in the wake of Robert's Rebellion - would be stripped of all of its lands, and - most likely - systematically executed. Tyrion might perhaps survive, much as Aemon Targaryen did up at The Wall, but the rest of the extended Lannister family (or what remains of it) is surely doomed to exile at the very least. Which, in turn, will create a pretty huge power vacuum up around Casterly Rock, and its 'Westerlands' hinterland. And, as it happens...
House Clegane May Turn Out To Be The Only Westerlands House That Doesn't Stay Faithful To The Lannisters
After all, the rest of the Lannister-ruled houses are either too obscure to be of much consequence, or too associated with Cersei, Jaime and Tywin to be likely - or indeed able - to betray their liege-lords in an effective enough fashion to take over after the war.
Sandor Clegane, however, last of his line, might just be able to win the favor of whoever takes over - however unintentionally on his part - and find himself a surprise lord of not just House Clegane, but the whole Westerlands, too. Which would be a) be a huge surprise, and b) exactly the sort of outside-the-box, leave-no-one-truly-happy ending that George R.R. Martin is apparently hugely fond of.
The Lannisters may finally have to pay the last of their debts, it seems - and Sandor Clegane may finally have to live up to some of his potential...