I nearly put this in the Things That Annoy thread but then instantly wondered about its use. Most of the time I’m baffled as to why characters in fantasy film/literature provide answers to quests in riddle form, particular when they’re trying to help that person. Why don’t they just tell them in plain English? Is it supposed to be a moral thing; anything worth having is worth fighting for, nothing should come handed on a plate, etc etc?
If you're writing a fantasy story, you might want your protagonist to initially misunderstand the information and go off in the wrong direction before realising their mistake. Why would a character give advice in riddle form? That would depend on where the information came from. A divination of some kind could be vague and open to interpretation. Advice passed down through generations could be in rhyme form to make it memorable.
I think sometimes the idea is that if the sage just gives them the answer, the protagonist won't understand or appreciate it, but by giving the knowledge or wisdom in the form of a riddle/metaphor/symbol they will fully grasp it. But that really only makes sense with deep proverbs. It doesn't make sense like in the original 'Mortal Kombat' when Katana told Liu Kang to use the 'element of life' to beat Sub-Zero. She could have just told him 'water' and saved him a few valuable seconds. This is off topic, but there is something called 'The Baker-Baker Paradox' (which I don't consider a true paradox) which may sort of support sometimes relaying knowledge in abstract ways (well, in fantasy books anyway).
But that doesn’t make it any more logical. If a traveler asks the wise old man where he can find the magic key, the wise old man, wanting to help, would typically say something along the lines of “When the sun has risen thrice, head north and look to where the tree which is not an elm, grows, for this holds the answer to your question.” When if he wants to help he could just say, “The magic key? Oh, yeah. In three days time you wanna head north until you come to a town. There’s an inn called The Sleeping Willow. Ask for room 12 and you’ll find the key tied to the underside of the bed.”
Maybe the wizard doesn't really want to help-help him. He wants to help the noob help himself by solving a riddle that will reveal... something? Like only the penitent man shall pass? You have to earn that magic key, bruh.
I think a lot of the time the one giving the riddles isn't 100% on the MC's side; often it's some sort of neutral third party. Maybe the MC has to convince them to even go as far as giving the riddle, or maybe it's transactional. You have a point though.
It could be a test. If the one giving the advice considers that advice to be a valuable commodity, they won't want to give it away freely to any fool who comes asking, they'd only want to give it to someone worthy. The riddle would then be a test to distinguish that worthy person.
It's actually a case of "Too real to be true" trope; that is, a real historical detail lifted into Fantasy that became an "unbelievable" trope. The origin of these "answer anything in riddles that are confusing" cases is the Oracle of Delphi, a sacred place for Hellenic Greece that their heroes and statesmen visited in case they wanted to have answers about the future or advice what they should do. Now you gotta understand that these advices and answers were given by young women intoxicated on various mushrooms and the sulphur fumes rising from the nearby caves, giving half-conscious answers that could mean anything. Now obviously if these women said "You will fight Xerxes at Thermopülae, suffer a defeat but your sacrifice will unite the city states" any slight deviation would disprove the oracle. So instead they said things like "Where the yellow perk perches, faces will flush red. You will stand on a heap of emptiness." Then people went like "Aha! I must fight the enemy at that place with yellow birds and we'll drown them in blood." If it didn't work out, they just went "nooo I misinterpreted the prophecy!" - just like in fantasy fiction.
To me, information presented/formatted into a riddle signals that that information is more important, more meaningful, something worth to pause for a moment and think about. I agree with those who say that it requires a moral superiority/purity to be able to read the riddle correctly or that a riddle serves for the MC to misunderstand what she is supposed to do initially. I am not sure if moral superiority is currently still used as device in fantasy--it might be outdated--or which other qualities have replaced it . . . . Regardless, riddles are plain fun.
In some instances, the person providing the riddle or other obscure assistance is somehow prevented from interfering in the events of the plot directly, and using something like a riddle is a way for them to provide assistance without violating that prohibition. I think that explanation can work if the author sets everything up well.
Because it's fun to say "riddle me this" before you ask a question. You should try it sometime. Like walk into a room, wait a second, and then say "riddle me this" and then ask a question. If it can work in real life, even better for a story. "Riddle me this! Why do people start stories with question?," he asked, as he blew into his pipe, bubbles pouring all over the floor.
I think it's cause most sages are super old and super bored. Rather than wave their cane and yell 'get offa my lawn' they devise an evil cryptic riddle to send the protagonist on. They purposefully send them to deathly hollows and dragon dens so that they run the risk of not surviving. Of course they always forget that they're protagonists and thus have plot armor, so they have to keep coming up with more riddles.
Ha ha! @OurJud has nailed an issue that has often bothered me as well. Not so much in fairy tales (riddles are kind of standard in fairy tales and/or legends and myths) but in a detailed story written in relatively modern times. I loved the 'riddle' in LOTR (the book) where Gandalf has to spend quite a bit of time at the back gate to Moria trying to figure out the password that would open the doors. The inscription says: Speak, friend, and enter. Turns out, the password is actually 'friend.' Gandalf, when he figures it out, laughs and says, 'those were simpler times'—meaning it actually wasn't a riddle at all, but a straightforward instruction given in peaceable times. THAT was a pretty good explanation for a riddle, at least in my estimation. Of course some riddlers are actually mischievous, and want to sent people on wild goose chases. Fair enough. The hero can return and strangle them later. But yeah. It can be annoying, if the riddle is deliberately created to be unclear. It's one of the reasons I'm not keen on puzzles or crosswords—especially cryptic ones. Why should I waste time trying to guess what somebody else cooked up to mislead me? Nope. Not really my thing. I'd rather go work on a real problem that actually needs to be solved.
I think that riddles are like prologues--overused and often unnecessary. But when they are done correctly, they can be quite powerful writing devices.
I don’t stance a chance with cryptic crosswords - my brain doesn’t process clues that way. My level is more: 8 across: Not dog but ... C _ t