Nothing rias did to get this hate, but a lot of fanfic writers who only watch the anime or read DXD fanfiction and get this wrong impression of her to think she some manipulative brat that doesn't like to train when if you read the light novel you see she just gave up on training be done with being compared to her brother, but Rias was a prodigy, but wasn't a monster in talent like her brother and became a Japanophile also Rias didn't know issei was going to be killed he was just given a pamphlet to be a customer also she could not have to tell what sacred gear he had at most koneko could have said he smell like a dragon that could mean two things one a dragon bloodline two a dragon type scared gear like twice critical.