well, i dont think Kaname is the true villain. I believe something is related to Rido because he is connected to him, and we know that Rido cannot die until Kaname dies. I believe Kaname had something to do with the death of Zero´s parents, and Sara used that, and now she told Zero, Zero feels like she is the only one who told him the truth. He feels that even Kaien cheated him. so, he hates Sara but somehow feels in debt with her, so he will not let anyone take her life.
I dont believe Kaname will kill Zero, or Zero will kill Kaname because:
- If Kaname killed Zero, yuuki would be pretty pissed off, she would stop loving Kaname on that precise moment.
- If Zero tried to kill Kaname, he would loose, because he still lacks power comparing to Kaname. Bloody rose can never fully obey Zero because:
- Zero drank Kaname´s blood, which makes him "obey"
- Bloody Rose is made of the heart of the hooded woman who had feelings for Kaname.
Although, Zero is the only hunter able to kill purebloods. He could easily kill Yuuki or other pureblood for example. Even Sara because the bloody rose obeys to Zero concerning other purebloods than Kaname.