Damn. Now that was a villainous monologue. I'm usually annoyed in scenes where the villain breaks down the hero with a crushing argument, but this worked well because it's highly rational and the heroine is an idiot.
Okay, confirmed. She's not a schemer, she's just an idiot. Which makes her luring her brother to his death kinda...weird, but I suppose we'll see.
Honestly, I don't think she has to do anything to get revenge at this point. She planted the idea in her head, and now the male lead is left with only two options: reveal his shallow love by refusing to give up his vampiric longevity and power, or agree to end up vulnerable when the plot runs its course, he collapses the family from his own stupidity, and his life is in danger.