Vriska in the story is a thief of light, a mythological role that is supposed to steal its aspect from others, the aspect of Light includes luck and relevance, which is what Vriska constantly manipulates in the story canonically. She is a manipulative cheater scum that does everything she can to stay in the spotlight which means she is constantly the center of the attention in the story, after she is introduced, and not only does absolutely awful things to many of the characters, but gets away with it because it was "relevant".
while many would think this is a very interesting approach on writing, in the end what truly happened is that the author and really bad parts of the Homestuck community got themselves WAY TOO MUCH attached to Vriska, ignoring her mistakes and changing her character completely to create some sort of "cheeky hero lady" which finally reached the conclusion of "this batshit insane twitter SJW was hired by hussie because she identifies herself as a Vriska "kin" to write Vriska's route in a videogame" and it was SO fucking awful that it finally broke the camel's back.
Vriska is THE character in the story to truly fullfil her role, she not only affected the canon plot, but many people reading and directly creating the content as well, and thats why she's awful, not only because she's a bad character(which she is after a certain plot point in the story, but not before), but because she completely destroyed its creators and led to a massive shitshow in the comic and outside of it
Vriska is a villain so good she destroyed the media she came from.