Does a cup-bearer have to be at a certain age? From what I understood, it was a grown man position in medieval times. Yet, we see Tywin becoming a royal cup-bearer at 10 or 11. Also, did the Mistress of the Robes have to be unwed like the ladies-in-waiting?

Ah, this one I can answer!

So GRRM has somewhat fused the office of cup-bearer with the office of page (although it’s complicated by the fact that he also uses the term page), which is creating the confusion.

From the ancient world through to early modern Europe, the office of cup-bearer was indeed an adult position of respect and influence. In order to prevent poisoning, monarchs appointed trusted men (or women, we have examples of female cupbearers in Beowulf as well as in the Bible) to serve them drinks and ensure they weren’t poisoned (sometimes doing double-duty as food/drink-tasters as well). Indeed, a sign of how important the position could be is that Sargon of Akkad, the founder of the Akkadian Empire, began his career as cup-bearer to the king of Kish, and that the King of Bohemia was given the office of Arch-Cupbearer to the Holy Roman Emperor during coronation rituals. Or for a less exalted but no less important version, you have the gentleman below, Sir David Murray, cup-bearer to King James VI of Scotland and future Lord Scone and Viscount Stormont.

By contrast, the office of page was an age-gated one, which sons of the nobility would likely occupy from age 7-14 before they graduated to be squires and then knights. Pages did odd jobs for their knight or lord – carrying messages, cleaning stuff, helping to arm and dress their master, etc. and for the purposes of this post, fetching food and drink for their master especially at table. In return, pages would be given room, board, livery, and education in the fundamentals of horse-riding and associated sports, combat, basic literacy, music and other pastimes, and above all, manners. 

As for the Mistress of the Robes, no she didn’t have to be unmarried: see Harriet Sutherland-Leveson-Gower, Duchess of Sutherland, Mistress of the Robes to Queen Victoria, who held the post before and after her marriage. However, ladies-in-waiting don’t have to be unmarried either; there were in fact different titles used to describe married vs. unmarried ladies in waiting, so that in England an umarried lady-in-waiting would be called a “Maid of Honour”; in France it would be “dammes” vs. “damoiselles”; in Germany it would be ”staatsdame”

vs. “

hoffräulein,” and so on.