I don't care what the reasons were, he didn't even bother to prepare me before-

[She shakes her head harshly. He doesn't understand. He doesn't get it.]

Let me spell it out for you, Zane. I am made with a very specific drive: to kill the living. It's a constant desire, whenever I'm around anything with a heartbeat. I want to kill you right now. I want to tear your throat out with my hands, my teeth, and watch your life drain away in a wash of red. I don't, because I have better control over myself than some mindless ghoul. But there will always be that want, that instinct.

Imagine that existence, where only other dead things are truly safe from your baser impulses. Imagine someone, undead, safe, becoming close with you. Demanding familiarity, comfort, touch. Now imagine them laying their hot cheek on your cold shoulder, this person who you had felt like you could be at ease around. Suddenly close, practically in your arms, and they are the thing you want to hurt more than anything in the world, and you had no warning, no time to prepare yourself for the change.

Now do you understand?