A little spoiler: What happens is that Some how people find out that Yuki became a pureblood and that info leaked out and Renn was told To kill Kaname, Yuki, and Rido-sama. But his Vampire side and his human side fight against each other... and Renn goes to Yuki and tells both her and Kaname that he was told to kill them. Then He tells them that eventually he will unless Yuki turns them into a pureblood... In my theory, When a pureblood turns a human into a vampire: one half of the blood becomes Vampire but since Renn is already a half-breed the human side is sealed out of his body and he becomes a pureblood but he said that as a favor Renn will kill Rido in turn for this and he suceeds... then in the ending... Yuki and Kaname get Married and oddly after Renn kills Rido He brings Shizuka back and steals her from Ichiru and Renn, Yuki, Kaname, and Shizuka. Are all pureblood Kurans now to continue the pureblood Kuran lineage