Trying my hand at this one:
Shen Yuan transmigrates into a worm.
It's just a normal garden variety (heh) earthworm, not a special magical worm (yet), so initially he thinks this is gonna be a really short transmigration adventure indeed. But of course that would be boring, so he also manages to end up in the body of a worm who lives under one of those magical immortal fruit-bearing trees.
One of the fruit drops, Worm Yuan chows down, and he significantly upgrades his physical abilities, and senses, and gains a cultivation boost! Hooray!
Unfortunately it's not enough to fix that he's still a worm, but it's enough so that he has less to fear from getting hit by a random shovel or such. In the process of eating the fruit, he sees some disciples (come to gather the fruits, slacking somewhat since they even allowed a few to hit the dirt) and overhears enough of a conversation to figure out that he's transmigrated into a worm that lives in the PIDW setting. Specifically, on Qian Cao Peak!
Wow! How random and wild! Why a worm??? What god did he piss off in his past life for this?
Well anyway, it is what it is, and Shen Yuan decides that if he's gonna live a probably short and uneventful life as a worm, at least he wants to see his favorite character. So he inches his way in what he hopes is the general direction of Qing Jing Peak, course-correcting whenever he gathers that he's guessed wrong, hitching a ride on the occasional shoe or once even gripping the internal part of a wheel from an An Ding Peak carriage, until finally, he's leveled up his meager worm cultivation even more and has reached Qing Jing Peak!
As Worm Yuan continues to inch his way across the peak, he keeps just-barely missing Luo Binghe, until finally he comes across... not Binghe, but a recognizable item: a fake jade pendant!
Though lost initially on a tree branch, it must have fallen at some point, down to the ground where Worm Yuan stumbled upon it.
Mustering his strength, Worm Yuan manages to get the broken string of the fake jade around his little worm body, and then makes the herculean trek to the wood shed. Dodging bird attacks, hiding from other QJP disciples, and further upgrading his Worm Skills such as digging, inching, and oozing, until finally he reaches his destination and squeezes under the door.
Leading to the situation of an incredulous disciple Luo Binghe -- who had previously been tending to his bruises -- watching as a little worm climbs into the shed (normal, usually it's spiders but sometimes other bugs get inside) while dragging his long-lost most treasured item in what can only be described as a deliberate fashion (very not normal).
After ascertaining that Worm Yuan is not some cultivator's tool or shapeshifted creature, Luo Binghe decides to approach this situation in the only reasonable way, and offers the worm some scraps from his leftovers. Worm Yuan happily shares a meal with his favorite character, and things take off from there.
Somehow Luo Binghe finds himself learning more about cultivation by watching Worm Yuan than he has in all his attempts to figure out his manual or listen to his shixiongs on Qing Jing Peak so far. He watches Worm Yuan work up the spiritual energy to crack rocks and scale the wood shed walls, and deduces some methods for applying his own spiritual energy in similar ways. He finds it heartening to think that if even a little worm can learn to cultivate through what seems to be pure determination, then surely Binghe can make his situation work, too. He scrounges around and manages to gather up enough materials for a makeshift terrarium, so Worm Yuan can be safe and cozy by his side at night.
Of course, trials and tribulations never stop. At some point Ming Fan and his cronies find the terrarium and smash it. Binghe is inconsolable until he realizes that Worm Yuan got away (extra durable, after all!) and is wriggling back towards him in a reassuring fashion.
Worm Yuan's hero schedule is quite full, too! At some point he digs his way into a tunnel to the Lingxi caves and saves Liu Qingge, and in the midst of the demon invasion he manages to help Binghe at a vital moment by hardening his body and tripping his opponent. He rides in Binghe's pocket when Binghe goes to claim Zheng Yang, too, developing his cultivation throughout it all.
Unfortunately, kind of, Worm Yuan is also in Luo Binghe's pocket when he gets thrown into the Endless Abyss. Through the hardships of the Abyss, Worm Yuan consumes some unsavory things (the less said about the quality of worm food in the Abyss, the better) but manages to unlock rare worm cultivation upgrades, until finally he achieves his first transformation -- a gigantic Dune-esque mega worm!
The less said about the symbolism of a stallion protagonist accompanied constantly by a literal monster worm, the better, probably. But having the ability to tunnel through basically anything does make a lot of things easier, at least in terms of travel, and cuts years off of the Abyss trip. Binghe and Worm Yuan almost have fun, even, just tearing through the terrain and any foes stupid enough to get in Worm Yuan's path until they retrieve Xin Mo and bust out.
Then they get into the demon realms and that actually is just straight up mostly a good time. Worms like Shen Yuan are not common so at first he nearly always surprises Binghe's foes when he shows up to help with fights, and a lot of the time the demons involved don't even seem to realize, at first, that he's with Luo Binghe and isn't just some hellish calamity that's coincidentally also shown up! But word gets around pretty quick that the new Heavenly Demon on the scene has a giant worm companion (probably leading to some misconceptions of people who think it's Tianlang Jun returned and that someone's mistaken Zhuzhi Lang's snake form for a worm).
Once that happens, unfortunately, some demons start taking precautions. After the first time Worm Yuan gets poisoned and nearly perishes (saved by Binghe's blood in the nick of time), Luo Binghe stops letting him participate in fights. Which is just rude! Worm Yuan's not going to make the same mistake twice, duh! But Binghe just keeps holding him in reserve again and again until the fight with Mobei Jun, and then when Worm Yuan intervenes anyway (is it just him or does Mobei Jun seem to know a lot more about potential heavenly demon weaknesses than he did in PIDW...?) and gets partly frozen, Binghe goes berserk. For a while there Shen Yuan is worried he won't actually LET Mobei Jun surrender!
Thankfully though he does, and then Binghe settles into his properties and starts... building a giant-scale worm garden? What about the harem, Binghe? Like obviously it's nice and all, but shouldn't you be focused on housing for, y'know, your future wives?
Other factions in the demon realms clearly are wondering about the same thing, as the marriage alliance offers naturally start pouring in. The most vocal of these being Sha Hualing. Worm Yuan supposed that his Binghe is probably waiting to officially take his wives so that he can marry Ning Yingying first or something, but still, a little planning wouldn't go amiss. Though eventually Luo Binghe seems to get -- if anything -- fed up enough with the questions about his marriage prospects that he does start setting up for a wedding.
Worm Yuan is surprised and touched when he finds himself being fitted for a monster-worm sized amount of wedding regalia. So he can be included in Binghe's wedding procession? That's so sweet! He's not sure he understands the inclusion of a veil, though...?
Anyway. Yes. Binghe marries the worm.
