Yuki & Zero

Having no where to go after the death of his family, Zero was taken in by the Headmaster, just as Yuuki was.

The relationship shared between Yuuki and Zero might be the most deep relationship in Vampire Knight. Zero was taken by the headmaster Cross and lived with Yuuki for 4 years before they became the guardians of Cross Academy. In the first night of his arrival 4 years prior to the story, Yuuki said that Zero looked unapproachable and she felt nervous, asking him for permission to clean his wounds the first night. As the two lived together, Yuuki seemed depressed by the fact that Zero despised Kaname, which was hurt by Zero when they first met. However, Yuuki did understand that Zero despised all vampires, especially purebloods, who murdered his family. 4 Years later, when Zero and Yuuki enter high school (Zero repeats a year, so he one year older than Yuuki), they became more closer. However, Yuuki still felt that a part of Zero would not open up to her. Later on, Yuuki discovers that Zero was actually a human which was bitten by a vampire, making him into a vampire too. Yuuki then began sacrificing her blood so that Zero can survive. Zero also mentioned that he would never let Yuuki turn into a vampire. However, later when Zero discovers that Yuuki is actually a pureblood and Kaname's little sister, the feelings change. It is unknown what is running through the head of Zero, but he keeps thinking about the older Yuuki, the one he came to knew, the human Yuuki. As for Yuuki, she desperately wanted to see Zero at first, and thus ran away (Hanbusa Aido and Akatsuki Kain had to follow her for protection). Despite the fact that Yuuki still had her deep feelings towards Zero, Zero did not feel the same way. When Yuuki was about to enter Zero's room, a gun was pointed at her by Zero. At that moment, it is unknown what was running in the head of both of them. Zero surely had to still have feelings for Yuuki, even if she turned into a vampire, and Yuuki definitely had her feelings too. However, Yuuki then said that the old Human Yuuki that Zero knew is now gone, and that she has been eaten up by the vampire Yuuki. That answer might have been to ease the tension between the two, but it is unknown if that is really what Yuuki is feeling after turning back into her pureblood self. At the last episode of Vampire Knight Guilty, Yuuki drinks the blood of Zero to prove to him that she really has turned back into a vampire. Zero is not astonished, but instead vows that a day would come when he would kill all purebloods, and Yuuki being one of them.

In the manga, Yuuki meets Zero after 1 year. When she touches him, however, Zero takes his hand away in disgust, due to the fact that Yuuki is a pureblood, which he despises.