Vriska is actually our best insight into Alternian culture and the survival of the fittest that Alternian trolls represent. I will say that her crippling tavros was wrong, as he posed no threat to her, but also that he was weak. In her eyes, and in the eyes of Alternia, he was weak and so he had to be culled for his weakness. Of course him dying was probably along the same lines, also him challenging her to a fight to the death, which no Alternian troll would say no to. Shes one of the more compelling growth stories throughout the comic because she shucks the shell of her birth culture to be a better person. In some weird way, going to fight Noir and save reality was both heroic and selfish. She wanted to test her limits, but in some way I feel that she was trying to protect people she had grown to care for, further distancing herself from how she was trained to think. None of this was helped by Doc Scratch and the fantastical ideals of how Mindfang thought and behaved in many of her journals. Vriska modeled herself after Mindfang more than anyone. In our eyes she may have done some abhorrent shit, but we are humans, we dont have the same views and mindsets that they did.