Given the benefits attached to the status and all those Disney movies, I have to ask, was impersonating a highborn person an occurrence during the Middle Ages? Were there any mechanisms in place to prevent a rich merchant from claiming to be a small unknown landholder from a distant part of the country (ala Littlefinger) or from another country entirely while being able to perform nobility financially?

Yep, it did happen! We know, in part, because there were laws passed establishing penalties for impersonating a member of the nobility. 

It tended not to be rich merchants who did this sort of thing, since they had the option of just buying their way in legit-like, but more often medieval confidence men and other tricksters who were keen to profit off the social mores or status of the nobility. 

If you were a well-off merchant, could you bribe your way into knight-hood/lower tier nobility complete with a grant of lands? Or was that rare, something that required unusual political circumstances, or both?

Yeah, you could, and you can find people complaining about up-jumped merchants buying their way into the gentry and the squirarchy and then into the ranks of knighthood as the 12th and 13th century. 

But as one professor whose lectures I listened to described it, it wasn’t like medieval England was marked by huge amounts of upward social mobility. Rather, what you had were spurts of ambitious social climbers and monarchs/nobles in need of cash, and then a good deal of social anxiety about what was happening to the old noble houses, and then people would redraw the boundaries, and there would be a pause – and then you’d have another spurt. 

The irony was that, because these social climbers were desperate to fit in, they often ditched any signs of their bourgeois pasts (including getting out of trade and into land) and fully assimilated into the value structure of the nobility, so that after a few generations (especially with intermarriage) you really couldn’t tell them apart. In this fashion, the professor argued, what you had was a ruling class that refreshed itself every so often with new blood but with very little change in ideas or social structure, and a very small amount of upward social mobility into the ruling class but a good deal of fluidity within the ruling class. 

Let’s say you were a common hedge knight with the skills/charm/crowd-working ability of someone like Lyonel Baratheon. Could you effectively be come a ‘celebrity’ tourney knight, for lack of a better term? And if you were making a lot of money off tourneys, what would be the best career move? You can’t invest it or buy land with it. Do you just take up service with a lord like most hedge knights? Try for an advantageous marriage? Or just spend your life touring and living in really nice inns?

Absolutely, you could become a celebrity tourney knight, and there were quite a few famous tourney knights in Medieval and Renaissance Europe. 

But in career terms, it was probably more likely for a tourney knight to find patronage (royal and otherwise) and from there gain estates or titles as a courtier

Stannis spoke of a “hard choosing” in Robert’s Rebellion between his brother or his king, suggesting that back then (and maybe up to now) he considered it his duty to back Aerys though he ultimately chose Robert. 1) Would this mean that he, personally–and the nobility, generally–didn’t consider Aerys’ acts as sufficient breach of the feudal contract to justify rebellion? 2) Does this have any implication on his future “hard choosing” between his daughter and his duty as Azor Ahai? Thank you!

First, I wouldn’t call Stannis’ political thought as representative of the noble class – he’s got some pretty unusual views about the nature of the monarchy.

Second, the reason why Stannis viewed it as a “hard choosing” is that, as a pretty strong legalist, he felt particularly torn between fidelity to his king and fidelity to his family. 

Third, I don’t think it does have an implication there. There’s too much evidence going in the opposite direction. 

Is “Kill the boy” (with or without foresight) this worst advice Jon ever received? Are we all overestimating Aemon’s wisdom, after all the same advise led Egg to Summerhall, right?

I hate to speak ill of the dead, especially Maester Aemon, but either “kill the boy” is one of the most misunderstood pieces of advice in the series or it’s one of the worst. 

Because if you look at how the advice shapes Jon’s actions in ADWD, it mostly leads him to push away his friends, ultimately weakening the support structure around him until there’s no one to protect him when the knives come out. 

Steven, you’re put in charge of creating some holidays for the major religions of Planetos. What significant events from each religion’s history would you choose?

Well,

For the Faith of the Seven, I’m thinking significant events: the Anointing of Hugor of the Hill, the first landing on the shores of Westeros, the Battle of Seven Stars, the founding of the Starry Sept, the crowning of King Aegon I, the birth and/or death of Baelor the Blessed. Oh, and days to praise each of the Seven, which we already knew about. 

For R’hllorism, I’m going to guess more solar-based events: the solstices, the equinoxes, the eclipses, etc. 

The worship of the Old Gods seems too decentralized to have holidays, but I could see holidays around the changing of the seasons, the harvest cycle, etc. 

The Drowned God thinks that holidays are for the weak. 

Is Top 10 really a good example of metahuman prejudice being done away with? Correct if I’m but aren’t robots the marginalized mutants of that universe? Plus, I think the Neopolis exists as a concentration camp city where metahumans are contained and kept away from “normal” people? Sorry, if this comes across as douchey?

I didn’t say it was a good example of prejudice being done away with – one of the things Moore does rather well is to show how prejudice changes and mutates over time. 

Rather, I said it was a good example of a setting in which you still have dramatic potential despite everyone being superpowered. 

Do you think any ghiscari masters ever try to treat their slaves well ? Or does social pressure make impossible it ?

Believe it or not, this was a topic covered very well by 12 Years A Slave. Yes, of course there were some masters who treated their slaves well – but the problem is that A. there are some rather strict limits to how “well” the slaves can be treated (freeing them is out of the question, as is treating them like a free person), and B. treating your slaves too “well” makes other masters view the non-conformist as a threat to the smooth functioning of the system. 

As with other systems of human oppression, slavery didn’t require participants to be actively malicious to function; it worked just as well if they were financially dependent, morally ambivalent, and socially surveiled.