Ok this is more of a headcanon but it is including Joysticks story, so basically: 

Mythical beings (like unicorns, elves,centaurs,...) were a part of the undertale universe but weren't sealed underground with the monster looking inhabits. Having looked to human, the mythical beings were kept alive to seal the monsters underground against their will. Only the mythical beings are able to use spells so they were used for their power but were feared the same time. Tho over the years they were hunted down and almost wiped out due to being "not human". Joystick is part of those mythical beings, being part unicorn but he was not killed by humans, thied to flee and ended up in the underground. 

Like monsters have magic 

mythical beings have spells 

And humans have powerful soul types

Nootnoot_The_Bean/Hananaki- being overly toxic, startling dramas out of nowhere, and possibly did faking (only says they have did when they get called out for being toxic)  the just generally make me verrrrry uncomfortable 

Fluffbunz- offering on characters that are nfs tagged multiple times 

bugereksiz- there is just... so much- Supports incest (dreammare) and regularly drawing it, alot of nsfw/fetshized art. Stealing character designs and showing no remorse (proof in link). Wantedme to make a custom based on my oc's which made me extremely uncomfortable and I'm happy I finally got rid of the characters I had from them. Blacklisted me for forgetting to tell them I gave away a character they made 💀 they're art just makes me so sick

Novamultiverse- Paying for characters and trying to get them even tho they were already sold, trading allegations, alot of drama around them I don't want to get involved with 

NeahChanArt- aloooot of incest nsfw art, fetshized sexual stuff that makes me really uncomfortable, just the whole boobymare think makes me so sick. I don't have anything against adding boobs to conon characters but they fetshise it way to much.