My guy WTFeather is learning and improving a lot. The shading in that Zelda piece is damn amazing and better than usual. He did exactly what one of the previous comments here wanted, and delivered it pretty well.
The anatomy is near perfection from my perspective, proper shades to define volume from a healthy plump female body and great muscle definition without overdoing. Just look at that abdomen and torso shading, you can discern this Zelda iteration has some fitness to her, but she's not shredded or extremely toned. Not talking about the line definitions in the middle, mind you, I'll comment about those next.
And finally, the cherry on top in my opinion, the skin folds/wrinkles. It is such a small and little detail, but a lot of artists overlook it so often or just draw them for the sole of the feet. Look at the armpits, she has some flexing lines on them and the belly folds created because of the postion Zelda is held in. It adds way more "realism" and appeal to the skin in my opinion. Even the navel can't be properly appreciated because of the same reason, Zelda's abdomen is flexing to the point her belly fat is folding on top of itself.
Nothing to say about the facial expressions, WTFeather found what worked for him and has been polishing it ever since, whether it can be same face-y or not, I don't mind it at all, for the expressions he draws nourish my tickle sadism plenty. They are so full of concern, fear, regrets, distress and forced laughter. Compared them to the really old Zelda pieces he did years back, I can't believe this is the same artist.
If anything, the advice I'd give now is, after he finds comfort with the new things he's been learning to apply, he could work on the foot shape variety, as not all people, and by extension fictional characters imo, share the same foot shape. You can find ways to "discern" it by the character design, ethnicty/inspired ethnicity or what a character does. Lets use Ruka as example. Ruka is 153 cm tall (5’0’’) and even if you don't want to take height into account (not all characters will have a specific number at hand) he drew her feet plump, quite wide, a round heel with round and quite short toes. Well, then Chizuru's (162cm / 5’3’’) could be a bit more slender, longer and shapely (meaning a more defined arch and less bigger and rounder heel), with longer toes. It might be a bit complex with his style, as the bodies he draws fit perfectly with the feet he draws, but considering what I've seen from him as off late, I'm sure he'll find a way someday, eventually. He should work and learn at his own pace.
Another thing is environments and set ups. It might not be his forte, and he might be focusing on polishing his charactes skills, but it'd be nice if he at some point worked on using something other that the Tickle Abuse-like contraptions, or the "lab looking" ones (that's how I call the white backgrounds, grey backgrounds and huge hunk of metal for contraptions). The tentacle walls, while not my personal cup of tea, are creative and variety, for example. Or one of my favorites, the Ochako Uraraka tickled by Himiko Toga one, where Ochako is inside a bean couch of sorts. Quite a neat twist to the "Throne" set up, and fitting in a sense (even though the room overall was quite empty). Sometimes trying to find a set up and contraption that can adjust to the characters and where they are from could work wonders for "immersion". Not that many care about it though lol, perhaps that's why he does not do it. I'm well aware it is a laborious task that differs a lot, and requires other set of skills and studies, from character based art so it is not a must and he can take as long as he wants until he decides to focus on it. Or just not do it at all too. Why fix what is not broken? If it works, it works.
Overall, it's quite noticeable that he has been studying and putting more effort into his pieces, to some more than others perhaps, I wouldn't know but I wouldn't blame him either. Sometimes you like some ideas better than others, can't be helped.
I firmly believe that, if he keeps focusing on his work, jump from one improvement to another, polish what he knows and keeps working on things he likes/has the hots for, he'll become one of the greatest of the artists around, at least for the people that do not consider him one yet.