About “Nagga’s Bones” on Old Wyk, do you think they are really the fossilized remains of some gigantic sea creature or they some other type of rock formation that the Ironborn have convinced themselves are proof of their legends? Related, do you think Sea Dragons are real, even if Nagga’s Bones aren’t?

It’s a good rule of thumb in ASOIAF that anything fantastical believed not to be real is, in fact, real. 

In other words, Septon Barth is always right.

In the politics of the seven kingdoms for the reach you mention that Garth X shows how difficult it is to lose the great game, what would be the cause of this difficulty? After all, it’s not like with the riverlands where everyone gangs up on a single ascendant kingdom but carving up a failing one, yet the reach shrugs off all the issues it had faced.

Because the Reach’s problem under Garth X was due to a temporary problem of weak leadership, rather than a fundamental problem of a failed state or a lack of resources.Thus, once Osmund Tyrell took over leadership, the Reach was able to pretty quickly rebuild itself. 

Does Westeros morganatic marriages? Is there ASOIAF analogous of the marriage of Archduke Franz Ferdinand and Countess Sophie Chotek in the differences between minor nobility and ruling house? Could a Cassel marry a Glover versus a Cassel marrying a Stark or an Arryn?

This is more @goodqueenaly‘s specialty than mine, but the case of Jenny of Oldstones and the Prince of Dragonflies would suggest that, yes, there are non-morganatic marriages. 

Some of your recent asks have got me thinking: did Edmure politically have much of a choice when the Northmen acclaimed Robb king? Could he have just not kneeled and had an awkward conversation with Robb and Cat later saying the Riverlands would be allies but not subjects? Would the Riverlords wait to kneel before Robb until their almost liege lord Edmure did? If they did not, does that force Edmure’s hand?

I think once the Riverlords knelt, there wasn’t much room for Edmure to do anything else – in addition to the very public statement that the Riverlords had just made about who they considered their king, there’s the fact that Robb has just very publicly saved the Riverlands, Riverrun, and Edmure himself from a humiliating defeat. For him to have backed out would have been seen as unbelievably, dishonorably, ungrateful.

But I don’t think it was the case that the Riverlords went first, either. Even before Greatjon stands up and acclaims Robb king, Edmure says “so you mean us to declare for Stannis?” – he’s already accepted Robb’s leadership as quid-pro-quo for his actions at the Whispering Woods and the Camps. 

Do you think a man like Petyr Baelish believes in the gods

Gods, I hope not. 

Because the sheer nihilism that it would take to believe in the gods despite having murdered every benefactor who ever aided you and took you into their household and then murdered your wife despite having vowed to protect her, to say nothing of all the poor saps you had murdered just for business (Ser Hugh, Ser Dontos, various Vale lords), or more precisely, to do those things despite believing in gods who would punish you for eternity for doing them, is quite frightening to think about.