Zero Kiryu

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

Personality
As a child, 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 However after Shizuka's attack, Zero developed a deep hatred and distrust of vampires, he became withdrawn and sullen. 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 people (humans), his cold attitude toward those he loves is likely to push them away and keep everyone at a distance.

Following his full awakening into a vampire, Zero harbours 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 the impresses upon her that its ok for her to burden and use him because he owes her.

He is even more agressive and rude towards vampires, however early on he shows hesitation toward destroying Level E vampires because they remind him of himself. Zero harbours 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.

Following the timeskip 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 spiralling 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.

Appearance
Zero has short silver hair with long bangs and grayish purple eyes that seem emotionless most of the time, they glow blood red when he loses to blood lust. He has very pale skin, even paler than the Night Class students. He is 181 cm tall. He bears a tattoo on the left side of his neck that seems to look like a cross between a star and a flower. It was supposed to keep him from turning into a vampire, and of which didn't seem to work. 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.

Background
Zero is descended from Vampire Hunters and was trained as a Vampire Hunter by Toga Yagari. Four years ago, Zero was taken in by Kaien Cross as the sole survivor of a murderous attack on his family by Shizuka Hiou. Zero was bitten during the attack and has spent the last four years resisting turning into a vampire. Zero was tattooed with a symbol on his neck that helped suppress the vampire awakening.

Plot Summary
Zero kept his vampire secret from Yuki until bloodlust overwhelmed him and he bit Yuki. Zero attempted to run away, stopped by Yuki, who pledged to kill Zero should he fall to level E. Following Zero's awakening as a vampire, his tattoo was used by Kaien Cross to allow Yuki to tame Zero. Zero's body rejected the blood tablets used to sate a vampire's thirst, thus Yuki convinced Zero to continue drinking her blood.

Zero harbored romantic feelings for Yuki, however he supported Yuki's feelings for Kaname Kuran. Zero prevented Yuki from becoming a vampire when attempting to trade for Shizuka's blood that would have saved Zero. He fought his master's compulsion and shot Shizuka to stop her biting Yuki. Zero swears he will never let Yuki become a vampire. Zero is prevented from drinking Shizuka's blood finding her already dead. In order to gain control and delay the fall into madness becoming a level E vampire, Zero was convinced to drink the blood of the pureblood, Kaname Kuran. Following Zero's discovery that Yuki is actually a pureblood vampire, Zero severed his friendship with her and likewise Yuki told him her vampire side "ate" her other side.

Though Zero regained his sanity, the Hunters Association have him locked up, arrested by Yagari. Kaname revealed that his purpose in strengthening Zero was in order for him to protect Yuki and defeat Rido Kuran. Zero is shot by his twin brother and finally completed the Twin Hunter fragment after he is convinced to "eat" the dying Ichiru. With this act, along with being a twin vampire hunter of excellent lineage who has become a vampire, within Zero is the blood of three purebloods, Yufki, Kaname and by proxy Shizuka, making Zero one of the most powerful characters in the series and saving him from becoming a Level E.

Zero's new powers are shown to be manipulation of vines within his body that are an extension of the Bloody Rose, which is capable of stopping Yuki's evolved Artemis Rod. Zero declared Yuki his enemy and attempted to keep her out of his fight with Rido. When Yuki struck the deadly blow to Rido's heart, Zero completed the destruction. Zero then turns the Bloody rose on Yuki and reveals his intention to kill all pureblood vampires including her. His memories of past Yuki fill him and he is unable to pull the trigger, yelling that it would have been ok if she had killed him instead.

Kaname interrupts the scene, but after a brief altercation he leaves Yuki and Zero alone. Zero once again feeds from Yuki, then kisses her, revealing to her that he loves her. Though he hugs her, Zero tells Yuki that the next time they meet, he'll kill her. As Yuki leaves the Academy, she sees Zero one last time, carrying Ichiru's dead body.

In the year gone by, Zero has been trying to find Kaname and hunting vampires on the hunter's list by night in an effort to sate his uncontrollable hunger at night. However, he has returned to the school, staying in an apartment owned by Kaien as he has been able to take the blood tablets. He does not trust Kaname's intentions with regards to his peace neogotiations, but decides to stay his hand because someone needs to control the vampires. He is to be made President of the Vampire Association in the future due to his strength and ability to intimidate others.

At school, he meets Kaito, another former student of Yagari and suspect Kaito intends to kill him, Kaito assures him that if Zero becomes violent, he will destroy him. Along with all the other hunters, Zero attends the negotiations and the party following. He becomes angry when he discovers that Kaito has brought Yori to the party as bait, but Kaito mocks Zero's ability to protect Yori, assuring him its an opportunity. Though Zero sees Yuki at the party and she acknowledges him, he remains unresponsive. When Sara goes to "help" Yori, he grabs the pureblood's arm away. Yuki interupts them and asks Zero to let Sara go, touching his arm. Zero snarls at her not to touch him, she says she will let go if he lets go of Sara. Zero snatches his hand away and drags Yori off as well, revealing that he smelt blood on Sara.

Later Aidou asks Yori and Zero to accompany him to see Yuki privately, Zero escorts Yori and leaves saying he doesn't want to meet Yuki. Zero's arm starts reacting and he smells blood, finding the scene of the dead hunter. When Yuki says she intends to investigate, Zero harshly rebukes her.