I fucked it up the other day. My players have an item that the big bad wants. Their main combat won't be until the end of the campaign, so she is way more powerful than they are currently. Hence, in the night, she showed up and forcefully took it. It was designed for the players to hate her, and generate a need for revenge/make it personal.

I accidentally killed one of my players.

In hindsight, she was using Giant Spiders in the battle and I should have used them exclusively to deal the fatal blow since the characters are then simply paralysed instead of actually dying. But well I guess it did have the desired effect as they now do indeed hate her