That is very relatable because I did the exact same thing. Here's a partial list of my own awful ideas:
It started with Marianne Le Fay (I didn't like the name Morgan, so I renamed her) being so called because she was friends with fairies in the French Alps, then shifted to her being a changeling child who was raised by fey beings after Uther and the rest of his hunting party was killed while hunting a wild boar in Broceliande. No adequate explanation was given for why a three-year-old princess was taken along to hunt a wild boar.
Camelot was actually named Caramel-Not. Bors told people in the foreign countries he was in while he had amnesia that he was from a camel-lot and it stuck. (Also, Bors converted to Hinduism, regained his memory, and decided never to go back. All this was mentioned offhand--he hadn't lived in Camelot for years and never showed up in the story).
Prior to the start, Mordred somehow drove every human apart from him and Arthur, who he kept mostly unconscious, out of Camelot through wild goose chase quests, falsely tarnished names, and more creative but always nonlethal methods.
Mordred isekai'd Guinevere to a world made of clouds. The first part of the plot was just her trying to get back.
Mordred stuck Agravaine, Gareth, and Gaheris on a boat and set it adrift so that listening to Agravaine singing "The Ballad of the Pickled Cabbage" would eat away at the others' sanity.
Gawain and "Gallahad" were best friends. Gallahad was kind of a rustic himbo, in contrast to Percival, who was older and had found the Grail before he showed up (I actually like the last bit's angst potential).
Lancelot was really evil and in league with Anna (who was evil). Guinevere, Gawain, and Gallahad all hated him.
Mordred was a sorcerer and had a strix named Deluge who wanted to be named Norman as his familiar. (I know it makes no sense but I still have a soft spot for corny socially awkward evil wizard Mordred).
Arthur and Guinevere were going to get their marriage annulled, then eventually remarry, because the marriage was arranged and also because when they first married, Guinevere was under a curse.
The whole thing began with a seventh-grade assignment to write an alliterative paragraph, so a weird number of words in the prologue started with the letter G. Thus, we have Gawain grappling a ghastly green ghoul over a golden grail (not THE Grail, apparently, but that isn't clear until much later) at the very start.
Pendragons could turn into literal dragons. Mordred, as Uther's grandson, could turn into one despite lacking the Pendragon name, since it was genetic, but Guinevere could also turn into one because she was a Pendragon by marriage. (The lore was a bit spotty). The climax of the book was going to be an epic dragon battle between Mordred and Guinevere.
There's a bit more of that sort of thing, but I'll leave it there for now.
so a few years ago, before I realised that there was such a thing as an Arthuriana fandom on Tumblr that I could mine for resources, I decided, in my infinite wisdom, to start writing a novel.
now where this goes off the rails is the fact that I a) did no research and b) had some pretty unusual ideas about the characters I was going to be using. having since found out some actual, concrete information on these characters, I thought it would be fun to go through my old ideas and see how fucking wild they are in comparison to what I now know the characters are actually like.
Kea's list of awful ideas:
morgan le fay was going to be a werewolf
king arthur was going to be colourblind and have a peanut allergy as his only identifying traits
lancelot was going to murder his abusive merchant father by staging a cart crash in the middle of the woods, then stabbing him in the confusion. for plot reasons
Nimue/lady of the lake and Lancelot were going to be adoptive siblings who were raised by the wild hunt (still kinda fuck with the siblings idea tbh)
Kay was going to be Arthur's dog.
Guinevere x Lancelot? nah, Guinevere x Lancelot's sister (also still kinda fuck with this, give that woman some lesbianism she deserves it)
the main villain was going to be some random ass faerie assassin called the Shrike, so called because it skewered knights on trees (I used to listen to far too much hozier, if you couldn't guess)
Arthur, Lancelot and Merlin were going to be in a polyam relationship and Guinevere, Nimue and Morgan were going to be in a polyam relationship, which, if you consider the two pairs of siblings in that collection, means that the family tree of these characters is literally a circle.
the Fae were going to have big fuckass bird wings for no particular reason other than I thought it would be cool
I have so many more of these, if this breaches containment I'll make another