I have now read a lot of fanfic for The Untamed / Grandmaster of Demonic Cultivation. I figured it was time to make some recommendations here for some of the best of them. It was extremely hard to weed it down to just four, and I had to struggle to try to keep them solidly distinct from one another (there tends to be a lot of overlap in fanfic) and generally happy (canon gives a lot of opportunity for angst). And not too explicitly graphic, although I compromised that one a bit.
So here are my four recommended fanfics, in order chronologically through events and also in order of humor, from heart-wrenching to hilarious:
DURING CANON, there’s always going to be a certain amount of angst:
Devoutly to Be Wished
by yunitsa
word count: 3,032
Summary: Five (and half) times Wei Wuxian fantasies about Lan Wangji, and one time he doesn’t have to.
Why I recommend it: I was going to keep this list of recommendations strictly non-graphic and then I realized that I had to include this one because it’s a gorgeous and heart-breaking look at the main character and his desire for his beloved as he grows and changes.
IN THE MISSING YEARS, there’s a surprisingly less angst:
Scapegoat
by astrobandit
word count: 1,325
Summary: four ridiculous things the Yiling Patriarch was blamed for, and one ridiculous thing that was positively his fault.
Why I recommend it: The canonical storyline switches between the past and the present with a good decade in between the end of the past and the beginning of the present, and in that time Lan WangJi appears to have decided that he has no more fucks to give and it is glorious. This story is a few very short vignettes that show just how done with everyone’s idiocy he is. Glorious!
IMMEDIATELY POST-CANON, specifically to the TV show
The Absolutely True Story of the Yiling Patriarch: A Manifesto in Many Parts
by aubreyli
word count: 19,692
Summary: In which the junior disciples (namely, Lan Jingyi, Ouyang Zizhen, and a reluctant Lan Sizhui) turn to RPF in an attempt to rehabilitate Wei Wuxian’s reputation so that he and Hanguang-jun can get together and get married and live happily ever after. It’s… surprisingly effective.
Why I recommend it: This is both beautiful and hilarious and does an amazing job of capturing that dichotomy that’s also present in the original story of balancing humor and drama.
FURTHER POST-CANON, our main couple are an established couple and dealing with other things:
A Civil Combpaign, and it’s companion, Besieged
by Ariaste
word count: 31,015
Summary: “And,” said one of the pompous ministers, “there’s the matter of a marriage to consider as well!”
Jin Ling, who at the beginning of that sentence had expected to slam into the very last wall of his patience and lose his temper entirely, paused. “A what?”
Thing was… it wasn’t such a bad idea.
Why I recommend it: This is side-splittingly funny. I had to struggle through some second-hand embarrassment but it’s worth it because this is the most awkward courtship attempt ever between two of the younger generation with our main couple established and looking on. And Wei Wuxian’s perspective on it all is an utter delight. Also, in some ways, this version of Wei Wuxian reminds me of Eugenidies from The Thief.
Biblio-therapy 
And okay, I’m going to add one more recommendation in the comments here because this story is amazing and was only excluded because it is so similar in timeline and plot and character development to “The Absolutely True Story of the Yiling Patriarch” and while it’s not as funny as that story, it is even more beautiful and poetic:
tell some storm
by aurail
https://archiveofourown.org/works/20983028?view_full_work=true
word count: 31,209
Summary:
In the aftermath of the events at the Guanyin temple, the cultivation world scrambles to understand their current reality. A man roams the countryside with a string of white in his hair. Another sits on the highest seat of power with a ribbon of red around his forehead. The younger generation turns out to be full of romantics. Nie Huaisang is to blame for everything, always. Jiang Cheng realizes that happiness has been more that 16 years overdue.
Wei Wuxian declares that it’s time that bitch pays up.
After a generation of war – much to the consternation of the elders, much to the delight of the young, much to the pleased shock of the subjects of the tale – the world welcomes a love story with open arms.
Ooh, I can’t wait to read these in like a month when I’m finally done with the original!