Zero Kiryu

Zero Kiryuu (錐生 零, Kiryū Zero) is one of the main characters of Vampire Knight. Zero is Yuki's childhood friend and the only other Cross Academy Guardian. Zero carries an anti-vampire gun named "Bloody Rose" given to him by Kaien Cross.

Personality
Zero was a quiet and gentle boy. His twin, Ichiru, questioned whether he was even capable of being a hunter. His gentleness even caused Yagari to lose an eye protecting him because he trusted an ex-human vampire. However after Shizuka's attack, Zero developed a deep hatred and distrust of vampires. Zero is a tsundere character, he sports a scary aura that makes most of the Day Class students wary of him. However, his innate nature is to protect humans, his cold attitude towards those he loves is likely to push them away and keep everyone at a distance.

Following his full awakening into a vampire, Zero harbors a great disgust towards himself because of inability to control his hunger and reliance on Yuki. His dismal outlook on his future and fear of what he might do causes him to give up and he almost kills himself. He fights to ignore his hunger to the point of starvation rather than go to Yuki. He tries to help Yuki resolve her own problems and then impresses upon her that its okay for her to burden and use him because he owes her.

He is even more aggressive and rude towards vampires, however early on he shows hesitation toward destroying Level E vampires because they remind him of himself. Zero harbors a great deal of anger particularly toward purebloods because of their mechanisms in his life in particular, he extends this hostility toward Yuki as well after she turns into a pureblood.

Following the time skip Zero still fights severe hunger and controls it by hunting vampires at night, however his fear of falling to Level E is abated thanks to Shizuka's blood. He retains the opinion that a normal vampire is always in danger of spiraling out of control. His desire to protect humans exceeds his desire to kill purebloods as he allows Kaname his peace negotiations, but expresses his doubt over Kaname's true motives. Despite his declaration of hostility against Yuki, when he meets up with an injured Yuki, Zero still finds himself assisting her and even almost allowing her to bite him.

Appearance
His appearance is a young man with a height of 186 cm (according to the official fanbook). He has short silver hair with long bangs and light lavender eyes. He has very pale skin, as pale as the Night Class students. He bears a tattoo on the left side of his neck. He is usually shown in his black "Day" Class uniform which he wears incorrectly with the vest and red tie exposed from under his black jacket, giving him a casual appearance and opposes the very neat look of Kaname Kuran. Zero often shown in promo art wearing different types of necklaces, he also always wears an earing that resembles a fang.

Background
Zero was born in a vampire hunter's family and had a identical twin brother named Ichiru. They, along with Kaito Takamiya, were trained as vampire hunters by Toga Yagari. Kaien later comments that they share a similar line of thinking thanks to this. In an incident, where the still naive Zero attempts to protect an ex-human vampire claiming that she was a nice person, the nurse turned wild and tried attacking Zero due to her Level E state. Yagari jumped in front of Zero to protect him, hence Yagari lost one of his eyes. This was Zero's first lesson on the dangerousness of seemingly innocent vampires.

Ichiru and Zero were once very close. Due to Ichiru's frail body, he could not keep up with training and lacks the essential skills. Ichiru constantly got sick, causing Zero to feel guilty about sharing their mother's love. One day Zero and Ichiru were taking a walk and Ichiru saw a women sitting in a tree. Ichiru was in awe of how pretty she was. Zero told Ichiru that it was a vampire and told him to stay away from her. Ichiru felt ashamed that he could not even tell a vampire from a human. Later that day, Ichiru over heard his parents talking about having to report that Ichiru would not any use as a Vampire Hunter. Ichiru ran out of the house and ran into the same vampire that he saw earlier that day. He saw that she was crying and asked her why. She told Ichiru that his parents killed her lover. A few days later, Ichiru runs off and Zero noticed the approach of the pureblood vampire before his parents did and ran outside. That vampire took Zero and bit him, hence turning him into a vampire. His parents came out in an attempt to save Zero but they got killed. Zero lay on the floor with his dead parents, and told Ichiru to run but Ichiru did not run away from the vampire who we later find out was Shizuka Hio. After that attack Zero was taken in by Kaien Cross, the headmaster of Cross academy.

Story Recap

 * Main Article: Plot Summary for Zero Kiryu

Zero fights to keep his secret from Yuki until he bites her, overcome by his hunger. Following his horror and depressed state, he makes an attempt to run away and kill himself, but is stopped by Yuki. Though Yuki attempts to save him from falling to Level E by offering herself to Shizuka, Zero prevents it refusing to allow her to become a vampire. Zero attempts to kill Shizuka, but as she escapes when he discovers his twin brother still alive and serving Shizuka and causes Zero to lose his chance to drink her blood before she is killed.

Zero comes very near to falling to a Level E state when Kaname convinces Zero to drink his blood. Zero supports Yuuki in her attempts to uncover hidden past, but the discovery and awakening of Yuki as a pureblood partner causes Zero to sever their friendship. Zero is locked up by the Hunters Association when they decided they cannot control him when Ichiru comes to him and convinces Zero to "eat" him to complete the "Twin Piece" fragment. Though enemies, Zero assists Yuki in killing Rido and shortly after he declares that he will kill all pureblood vampires including Yuki. He fails to kill Yuki, instead he reveals his feelings for her and they part ways.

Zero now finds himself poised as the future president of the Hunters Association. In this capacity, he is forced to attend the peace meeting between the hunters and vampires and the vampire ball, while there he sees Yuki again for the first time in year. Zero continues to hunt vampires and seeks the truth about the Hunter's death at the party. Meanwhile he is still dealing with issues regarding his loss of his humanity.

Trivia

 * Zero was born in the year of the Dog.