• In literally the second line of the book, Tolkien implies that Bilbo Baggins wrote a story which was preserved alongside the in-universe version of the Mabinogion (aka the best-known collection of Welsh myths; I promise this is batshit). This is because The Hobbit has been preserved, in Tolkien's AU version of our world, in a "selection of the Red Book of Westmarch" (Prologue, Concerning Hobbits). If you're a medievalist and you see something called "The Red Book of" or "The Black Book of" etc it's a Thing. In this case, a cheeky reference to the Red Book of Hergest (Llyfr Coch Hergest). There are a few Red Books, but only Hergest has stories).
• not a medieval thing but i did not expect one common theory among hobbits for the death of Frodo's parents to be A RUMORED MURDER-SUICIDE.
• At the beginning of the book a few hobbits report seeing a moving elm tree up on the moors, heading west (thru or past the Shire). I mentioned this in another post, but another rule: if you see an elm tree, that's a Girl Tree. In Norse creation myth, the first people were carved from driftwood by the gods. Their names were Askr (Ash, as in the tree), the first man, and Embla (debated, but likely elm tree), the first woman. A lot of ppl have I think guessed that that was an ent-wife, but like. Literally that was a GIRL. TREE.
• Medieval thing: I used to read the runes on the covers of The Hobbit and LOTR for fun when I worked in a bookshop. There's a mix of Old Norse (viking) and Old English runes in use, but all the ones I've noticed so far are real and readable if you know runes.
• Tom Bombadil makes perfect sense if you once spent months of your life researching the early medieval art of galdor, which was the use of poems or songs to do a form of word-magic, often incorporating gibberish. If you think maybe Tolkien did not base the entirety of Fellowship so far around learning and using galdor and thus the power of words and stories, that is fine I cannot force you. He did personally translate "galdor" in Beowulf as "spell" (spell, amusingly, used to mean "story"). And also he named an elf Galdor. Like he very much did name an elf Galdor.
• Tom Bombadil in fact does galdor from the moment we meet him. He arrives and fights the evil galdor (song) of the willow tree ("old gray willow-man, he's a mighty singer"), which is singing the hobbits to sleep and possibly eating them, with a galdor (song) of his own. Then he wanders off still singing, incorporating gibberish. I think it was at this point that I started clawing my face.
• THEN Tom Bombadil makes perfect sense if you've read the description of the scop's songs in Beowulf (Beowulf again, but hey, Tolkien did famously a. translate it b. write a fanfiction about it called Sellic Spell where he gave Beowulf an arguably homoerotic Best Friend). The scop (pronounched shop) is a poet who sings about deeds on earth, but also by profession must know how to sing the song or tell the story of how the cosmos itself came to be. The wise-singer who knows the deep lore of the early universe is a standard trope in Old English literature, not just Beowulf! Anyway Tom Bombadil takes everyone home and tells them THE ENTIRE STORY OF ALL THE AGES OF THE EARTH BACKWARDS UNTIL JUST BEFORE THE MOMENT OF CREATION, THE BIG BANG ITSELF and then Frodo Baggins falls asleep.
• Tom Bombadil knows about plate tectonics
• This is sort of a lie, Tom Bombadil describes the oceans of old being in a different place, which works as a standard visual of Old English creation, which being Christian followed vaguely Genesis lines, and vaguely Christian Genesis involves a lot of water. TOLKIEN knew about plate tectonics though.
• Actually I just checked whether Tolkien knew about plate tectonics because I know the advent of plate tectonics theory took forever bc people HATED it and Alfred Wegener suffered for like 50 years. So! actually while Tolkien was writing LOTR, the scientific community was literally still not sure plate tectonics existed. Tom Bombadil knew tho.
• Remember that next time you (a geologist) are forced to look at the Middle Earth map.
• I'm not even done with Tom Bombadil but I'm stopping here tonight. Plate tectonics got me. There's a great early (but almost high!) medieval treatise on cosmology and also volcanoes and i wonder if tolkien read it. oh my god. i'm going to bed.

• Valinor did not have some special light-emanating trees and they did not actually die, it's just a nature myth that metaphorically talks about a period when the sky literally darkened; this was caused by some unknown natural disaster (like the explosion of a supervolcano).
• references to Tree-light and Elves being enhanced by it is just Noldorin propaganda. 

• there are various theories as to what they really were (religious artifacts? some mandate of rulership? just really pretty jewels and everybody exaggerated how special they were? some kind of a super weapon?), but also more philosophical suggestions that the Silmarils are the elements of air, water and earth itself (hint hint that's why they eventually become part of these), and the struggle over them represents the struggle over rulership of Beleriand/Middle-earth. that in the end the Silmarils aren't really possessed by anyone reflects how all kingdoms eventually fall and nobody under Eru can be a master of the world. 

• like who even is that great and perfect?
• he's probably just some kind of a bogeyman made up by the Sindar
• did anyone in Beleriand ever even see him? CONVENIENT that he spontaneously combusted almost immediately after he came to Beleriand
• also who names their kid "the spirit of fire"??? what if it's not a personal name of any elf but more like a title? or a name associated with some entity that had religious following in Valinor?
• there's a clue to this in how Fëanor's supposed sons are mostly referred to as "the sons of Fëanor" or "Fëanorians": it bears thinking that they were not actually related to one another, but "Fëanorian" was a title in a same way that "Fëanor" was a title. It doesn't mean an ACTUAL son to a guy named Fëanor but a devotee to whatever the entity or title named Fëanor represented. 
• (they couldn't be real brothers because there just can't be that many hair colours in one family.)
• MAYBE FËANORIANS WERE SOME KIND OF A CULT
• it was probably some kind of a death cult obsessed with blood and murder, considering their body count 
• also because of this they were kicked out of Valinor and all stories about how they WANTED to leave are propaganda. 

• How else do you explain the different versions about who he was?
• the one who fathered Celebrían was Galadriel's real true love, but he died in obscure circumstances
• this theory you don't really want to talk about much, because you don't want to insult Queen Arwen. Also the current Celeborn may come after you. 

• his first death is a symbolic one: he had been estranged from his relatives and people, but by marrying Lúthien he completely leaves behind that life and "dies" as a member of the House of Bëor to become a part of the House of Elwe
• he did not come again among Men after marrying Lúthien, in other words he was dead to his original society
• the sequence in Mandos where Lúthien pleads for pity was originally a description of a courting scene that got bastardised along the way; she had to go to the remaining members of the House of Bëor and ask for Beren's hand in marriage. They would not agree unless Beren gave up his claim to the title of chieftain, i. e. he has symbolically died. 

• that's why Doriath lasted so long, Morgoth was still scared shitless of her and didn't dare go anywhere near her
• Nan Dunghortheb was literally her backyard!!!
• why else Lúthien would be able to weave weird dream cloaks???

• the idea that he was a dog came from: 

1. he was the best tracker in Aman, so in Beleriand he was called "The Hound of Valinor". Later generations thought this literally meant he was a dog.  
2. whoever wrote down the legends about him was a wishful idiot who loved dogs and wanted them to be able to talk (understandable)

• aside from the obvious, of course
• were Aredhel and Eöl really his parents though? was Aredhel even married to Eöl? 
• maybe Maeglin was a thrall of Morgoth, or was born in captivity and brainwashed to be loyal, and his task from the beginning was to bring Gondolin down
• Aredhel did leave Gondolin like the Silm says, but stuff did not go down like the story tells. 
• -during her wanderings, Aredhel somehow found Maeglin and saw him as her shot to stage a coup in Gondolin by claiming he was her son (and male heir for the kingdom). Eöl never existed. Or if he did, he was a random guy Aredhel met and used to her own ends. 
• Turgon found out about Aredhel's plans (but not about Maeglin) and he was the one who actually killed her.
• maybe she was a Fëanorian cult member in secret and was trying to take over Gondolin for them

• nobody can get up to that much weird shit
• the real Túrin probably died in Doriath and Melian covered it up

• if you subscribe to "Fëanorians were a death cult" theory, then Maglor is actually an ominous cryptid that foretells misfortunes. 

• Thranduil is aware of it and in fact he has helped to keep it secret all this time.

• Eärendil is a half-elf, actual Star and God's favourite little guy. He has a flying ship and travels in space. He keeps an eye on Satan himself. His birth was foretold, he fought and killed the biggest dragon in history in a massive air battle that caused an entire mountain to collapse, and he may have killed Ungoliant. No real person is that special. 
• Elwing wouldn't do what bunch of men (who were maybe in a death cult) told her, she's obviously a villain if she existed. She can't die (was directly prevented by divine powers when she tried to) and chose to be immortal. Also being God's favourite little gal and having the ability to turn into a bird? Very suspicious. 

• the ruling line had many problematic characters that were not well suited to the role
• it also culminated in Ar-Pharazon and all the tragedy that his actions brought
• Silmarien inherited some of the most important heirlooms from the First Age, which proves that even her father thought she was the true heir
• also Silmarien's descendants survived to maintain was what left of the culture and wisdom of Númenor; further proof of Silmarien's right.

“Frodo deserved all honour because he spent every drop of his power of will and body, and that was just sufficient to bring him to the destined point, and no further. Few others, possibly no others of his time, would have got so far.”

• 1 - Oath-Bound: You can spend 10 minutes in meditation in order to sense the general direction of the Silmarils. You can sense the directions of all three of them at once. You may do this accidentally if your mind drifts for long enough; you often wake from sleep or reverie thinking about them.
• Also 1 - Enduring Fire: When you go down to 0 HP no you don't, you go down to 1 HP instead. You can do this once per Long Rest. You do not have a choice as to whether or not this happens.
• 2 - Lighting Sparks, Fanning Flames: You have Expertise on any Persuasion or Intimidation checks relating to the Oath.
• 3 - Kinslayer: When in direct pursuit of a Silmaril - eg, it's within 120ft of you and you know it - you have Advantage on all attack rolls and make a critical hit on a 19 or 20.
• 4 - Spirit of Fire: When you roll a natural 20 or a natural 1, the nearest flammable object within 120ft of you which is not worn or carried by another creature catches fire, just kind of for ambiance. It will not go out until put out.
• Also 4 - Forsaken: You are resistant to magical damage by any caster or creature classifiable as "divine." You serve something worse, now.

• Fingolfin - as a letter from Doriath is smudged in just the right place. This misunderstanding helps to contribute significantly to his decision to get crushed by Morgoth’s boot.
• Caranthir - he ignores most of the going’s on from his siblings and would really like to know less about the supposed marriage of his hated cousin and least favourite brother. May they make each other miserable together. Doesn’t find out the truth until Doriath.
• Angrod - he is torn between brotherly loyalty and loyalty to one who is his friend. He isn’t sure which one to feel sorry for and is Very Relieved when Finrod clears up the misunderstanding.
• Finarfin - garbled rumours from across the seas. Is absolutely horrified and thinks it is yet another rebellion by his daughter. Doesn’t find out until he sees Galadriel again in Beleriand, where his first words upon greeting Celeborn are ‘thank the Valar you aren’t my nephew’
• Sauron - attempts to torment Galadriel about the loss and downfall of her husband. Is very confused when she tells him that he is alive and well and that Sauron has had dinner with him! He does not recall dining with any of Feanor’s sons. He just knows that somewhere Celebrimbor’s ghost is laughing at him.
• All of the above.