Vriska is a character from the webcomic Homestuck, she's become kind of a meme and as I am aware was the first one to start the whole "X character did nothing wrong" meme.
Being the Vriska of a show is pretty much being a cunt that the fandom likes and defends, sometimes they have reasons (Like Catra or Lapis) and sometimes they don't.
If i don't recall bad, Vriska threw a wheelchair dude into a pit and/or was the reason why he lost his legs, she's kind of a bitch. >>107948187
May god bless you