i get it, but at least someone helped you. People sometimes have no shame
Your sister is smart for hiding the watermark. I noticed people go on tiktok or twitter if their design gets stolen, but i fear that you might get in trouble for "angry mob" coming at stealer
Uh oh, are you sure it wasn't you???
You started this thread https://forums.tapas.io/t/wanna-be-art-moots/641559 and on the twitter linked there, https://twitter.com/cal_calliope6 - which I am absolutely sure it was yours, as you followed me and other people from tapas - I'm 100% that there sure you posted work stolen from this artist https://twitter.com/muisketeer7
Wish I could provide more concrete proof but the calliope account seems to be deactivated and alas, I did not take screenshots. (Though, some evidence can be found googling "calliopetrichor".) I did not want you to call you out publicly but since you are posting in this thread...
So my point in this post would be, idk, I guess at least admit what you've done? Kind of hypocritical of you to post in this thread when you were an art thief yourself. If you are absolutely sure that twitter account wasn't yours, I'd like to know how do you explain the following thing. If you do have an explanation for that, I'm sorry for placing a fake accusation here.
For art it's happened a lot (at least when I used to do fanart and more anthro art) at one point I got accused of stealing my own art as well, as I had someone calling me out for stealing my art from me x.x (I had posted in a forum some fan art that I did, and they called me out saying that I didn't draw the art because they bought this art at a convention from this artist with a link to my dA. I had to explain, that yea... 'you probably bought my art from me at that convention')
For my comics not as much, it gets reposted a LOT without my permission (which sucks because I need the adrev and views for the algorithms on the sites I do post it on), but usually credits me as the artist x.x (a lot of these are also translation sites, usually Spanish)
Had a few trace and recolours as well of promotional art when I was doing an anthro comic, with people claiming the art to be their original art... when it was not.
Had someone claiming to be me at some point / not sure if they are still going honestly (I occasionally get something like 10 - 15 pms in one day asking if I am the same Kura in game/chat server) Got someone complaining to me about self promotion too, on how they promoted my comic in their series as I had requested but I have yet to promote his series in mine and it was not fair.
Their old Tapas account saved on waybackmachine: https://web.archive.org/web/20210908131903/https://tapas.io/Writenry5
A number of things that they claimed to have drawn are stolen artworks, a few from the person you've already mentioned.
https://mobile.twitter.com/muisketeer/status/1389985405437714437/photo/34
https://twitter.com/muisketeer/status/1414948740452999173/photo/11
https://mobile.twitter.com/muisketeer/status/1387519878588940289/photo/31
Jenny Yu
https://twitter.com/Adobe/status/872570438752256000/photo/12
https://www.maxitendance.com/2019/01/illustrations-artiste-jenny-yu.html1 [I don't know the regulations on using other artists' works as covers without permission, but it's about 7 images down]
More novel cover artwork:
Tom Haugomat
Xuan Loc Xuan
https://twitter.com/xuanloc_xuan/status/1090267278623424514/photo/1
https://ego-alterego.com/night-illustration-xuan-loc-xuan/#.V9PMOpCg9jQ [4th image down]
A wallpaper [and gif apparently]
https://chikyuuwallpaper.blogspot.com/2021/05/1024-x-576-pixels-aesthetic-wallpaper.html [about 12 down]
As for the remaining four, Google reverse images can only provide so much. They claim that they drew the cover for "Purple Shades of Blood", but as far as I can tell, they are two images overlaid each other.
They seem young and naive, hoping they could get away with this, and it almost seemed like they did... but it's hard to scrub your tracks entirely from the Internet.
Just a message to folks, especially younger, impressionable ones, don't steal other people's art work and claim it as your own. You will regret it one day, especially when you really do want to move on and create your own works.
LOL! Sorry, that's funny XD. But it's forgivable bc they're only being a vigilant fan looking out for you, lol. Did they realise that it was you in the end, though? If they continued to harass you after the fact, then I can see where that can be annoying and problematic.
@frgmnt And @incognito-burrito And I followed them on Twitter! I've been had!
Went and followed the actual artist, but to be caught up in a scheme such as this... the shame 
It seems a few people followed them when they made that first forum post. The original artist is phenomenal, though!
Naw it was pretty funny, and yeah they did do a "oh, I see." kind of response after I replied. So thankfully it wasn't a fight with them and like you said, they were just looking out for me without realizing it was me lol
I haven't caught people reposting my art or comics, but there's one thing I made that gets ripped off a lot. Reposted without my permission to sites like 9gag, facebook, twitter etc. I've even seen bad SVG traces of it being sold on t-shirts and mugs. It's hilarious and annoying to me because it's THIS:
It was originally posted on my Tumblr3 after in a frustrated state, I scribbled it at about 11pm one evening, then went to bed, only to wake up seeing it had exploded. Occasionally people ask for permission before using it... mostly they don't.
I wouldn't even care if people weren't making money off it that I never see a penny of. 
I think I have seen that flowchart before in a different style.
My art has been uploaded by someone else at DeviantART too at times. If someone tells me, I just report the artwork and move on. Other than that I have no incidents.
I don't understand not asking to repost something, i asked people on here who offered to draw our characters for practice to repost ( which is bare minimum since it IS their artwork)
@incognito-burrito @frgmnt
Wow ive seen Writenry around the tapas forums, often promoting their Purple Shades of Blood. I knew its cover was commissioned by someone else. I didnt think they would claim to have drawn the cover, and even steal other artists' works. Dang ive been had
Unfortunately, you're not the only one. What's worse is a lot of their readers still believe their story, some of them are even in this thread. I've noticed since @frgmnt's callout post and my follow up of evidence, they have deleted their claims of 'impersonated art theft', the thread 'wanna be art moots' and changed their username AGAIN, this time to mewmewmew. I hope that they've learnt a lesson from this and will stop with their deception, but time will tell.
Yeah I really hope they're just a young naive person who thought could get away with it, like it was mentioned earlier in this thread. I hope they'll learn from this experience. The lesson from this is that no art theft goes undetected, particularly online.
(I sort of had a hunch something was off when I followed them - a very skilled artist, coming up from out of nowhere without a prior following? ...Not to say this doesn't happen but still, sus. But I didn't actually know about the theft until I saw on twitter the accusations from muiskeeter. 
)
As for me, I've never had my art stolen to my knowledge, but the possibility of that is one of the reasons why I sign my work.
This may not be connected since i am a novel writer and I don't have any talents when it comes to drawing, but there's this bl author (an artist too) which I knew. She filed a lawsuit against the culprit who posted her comics on illegal sites. Since she cannot track the person who posted, she asked help from her fans about tracking that culprit. In exchange, she pays them fairly. This is an example of copyright and plagiarism I guess... and in your case, you can always report the person who stole your works. But if you don't prefer filing a complaint, you can always find a way... there are lots of them..
Don't let your works get stolen guysss so better put watermarks that only you can know. You may put 5 watermarks, blur it, make it visible only to you, have it in a little size or what. Your efforts are part of your hard works so have yourself stand for justice
Thank you and take care
@frgmnt @incognito-burrito @euphisa The brazen attitude to come to a thread where the OP, myself, has actually gotten their stuff stolen, and then turn around and claim a similar thing happened to you only to be the perpetrator of art theft... Like, excuse me! Why? Were they trying to get caught?! I wish I screenshotted their original post, if only I'd known.
They are most certainly young and naive. When you're online, it's fun to make up a persona about yourself (which is what this person did; the clues in their posts are obvious), but you draw the line when you steal others' works and claim it as your own. Even if the person erased their tracks, there are ways where it can still be found (waybackmachine is one).
One of the huge red flags was definitely the skillset, but also the wide and varied styles. People can have more than one, but none of theirs carried a similar feature that defines an artist's signature, you know? Another thing was, if they already had such an amazing art skill, it seems odd they'd often ask for collaborations with comic/concept artists etc to draw for them.
I feel badly muiskeeter was taken advantage of then hoodwinked by the actual culprit into thinking they were the good guy, but she's moved on and has since taken extra precautions with her work. Would pulling her back into this mess and telling her that her initial assumptions about them were right do her any good now? I don't know...
It's crappy that artists have to go through such lengths to protect their own work from theft. You'd have to put watermarks everywhere now. 🤦♂️
What's funny is that they've posted about one of their written works being posted on one of those... novel sites without their permission. It wasn't stolen, per se, since their name was still credited as author, but it was just hosted there without their consent (and they often have a written statement on their bios that they do not want their works to be reposted elsewhere... the irony and hypocrisy...).
But obviously, they didn't want to be caught and that was their way to deflect their actions--make up a fake person to take the blame, look like the hero (claiming to have helped the twitter artist muiskeeter (the artist that they stole from) confront the 'art thief' after muiskeeter confronted them about it. Unbelievable, really...), and also be the victim at the same time, since they were being rightfully blamed as said art thief.
Screenshotting the actual 'art moots' post might be an extra boost, but all their posts are littered with evidence (I've also just screenshot a lot of their threads with their currently changed username (AGAIN--two in one day it seems) to seawater. And as I'm typing this, I've also noticed they've changed their avatar). Unless they decide to actually make up an entirely new account, they would be sacrificing the views, likes, and follows on the novels that they've already posted on Tapas. And seeing how often they've promoted their works (particularly Purple Shades of Blood), even under a different username, it would be clear who they were.
Yea, I notced the name change, but they didn't change the PFP, in another thread where they were asking for a critique. So, do you know if the art is the only thing stolen? Cuz I'm suspicious of any content they claim to be theirs.
Edit: Oop, they cahnged their name again, now it's emo_infp, qith a different PFP. Since you can't delete topics, and even if a mod closes it anyone with a link can still access the topic, this will never go away.