Tolkien's Bastards: Why Certain Fantasy Tropes Stick
Of course there are plenty of authors who write in the fantasy genre, while gleefully ignoring all of these tropes. But what's fascinating is that those are the exceptions that prove the rule, they are almost defined by the absence of certain tropes. They're painting in the negative space so to speak.
The Secret Prince
One of the most enduring tropes of fiction, and fantasy in particular, is the discovery of hidden ancestry. The peasant hero must be the secret son of the king. It's present even in stories in which the heritage plays no apparent role until the very end. The commoner saves everyone, by the sheer effort of yanking himself up from dirt farming, but the punchline to the story will nearly inevitably be: plus you're secretly heir to the throne! Sure, it gives the hero a great reward to round out the story, but there's also a layer of utterly regressive explanation to it. Ah, part of our mind can say, that's why nobody was able to be somebody, because they were actually somebody to start with.
The Bourgeois Peasants
Outside of the strain of gritty fantasy like George RR Martin, which tries to create a world true to the society of the middle ages but with magic and dragons and such tossed in for fun, you just don't find rural poverty in fantasy novels. And more than just lacking the crushing violent serfdom that actually characterized the world of the commoner, fantasy novels have a very particular vision of the commoner. And it's one very familiar from both American and British mythologies of their own history. Peasants in fantasy are almost without fail well-educated land owners. Self sufficient with some of their crop, selling the rest for a profit. Invariably there's an old sword hanging above the mantle, to be taken down in case of banditry. They are the prototypical Jeffersonian yeoman farmers. Illiterate? Chained to the land? Virtual chattel? Not in fantasy.
The Evil Empire
It's really very simple. There is good and there is evil. Which means that there are good nations and evil ones. There will inevitably be one that is the big bad evil one. It will be a dictatorial empire ruled by a terrible tyrant. Said tyrant's goals will include (but not necessarily be limited to) conquering every square inch of the planet, enslaving the population, and ... well that's about it. They're just evil okay? This appeals to some part of our mind that likes the world to be simple. It likes there to simply be identifiable bad guys so we can go land on Normandy.
The Enslaved Monsters
Goblins, orcs, trollocs, trolls ... the list of only slightly differentiable big, ugly, stupid creatures that border on the animalistic goes on and on in fantasy. Generally the creatures are morally irredeemable, tainted through some dark magical creation, and are commonly referred to as slaves. The latter is especially interesting because although these creatures are given no freedom, they are never rescued, never granted freedom by which they might attain the light. The sword is the only answer to their existence, the only release they may ever know. Part of this goes hand in hand with the stark contrast of good and evil in fantasy in general, but it gains further emphasis by the notion that the armies of evil are composed of the unwilling. It's a cop out of morality, a literal manifestation of the enemy as the other. And those who are willing, the ringwraiths and such, they are portrayed universally not as the other side, but as traitors. All wars in fantasy are race wars.
Fantasies don't have democracies except on occasion when there's a merchant nation over in the corner of the map that the main characters get to around book four. Said nation is almost invariably overwhelmingly corrupt. Some of this pattern is the simple mimicry of a medieval world. Kings and nobility go hand in hand with swords and charging knights. But with a literate and financially well off populace, all the seeds are planted for someone to just demand a damn election already. It's one thing when gritty fiction features kings, but quite another when the more idealistic fantasy fiction systematically casts the good nation as a hereditary monarchy.
During one of their little writers' group meetings in which Tolkien began reading aloud his next chapter, C.S. Lewis is famously reported to have remarked "not another fucking elf." There's certainly a strand of fantasy that has tried to bring the old fairie implications of elves back into play, the terrible cruelty of immortal beings, but the Tolkien archetype has stuck fairly well of gorgeous immortal creatures living in the woods and mastering the art of the bow.
Terry Pratchett aside, it's amazing that of all the possible configurations of worlds once physics and science are removed from the equation, the plain old ball of rock tends to be the one we return to. It's evidence of just how situated we are in a scientific era, that worlds simply are round. We actually cast our vision of the world into fantasy, unable to suspend disbelief otherwise.
This list is not intended as criticism. It's certainly not meant to say "fix these damned stupid things that I'm sick of or I'll find a new genre." But it's fascinating to hold up to the light the things that recur over and over again in our fiction, to see what those themes are reflecting back to us about ourselves.