Personality:

Naturally due to his past experiences, Zero is a character that does not give his trust easily. Living with Yuuki for four years, she didn't realize he was a vampire until he'd actually attacked her for the first time. He never told her that he was from a family of Vampire Hunters or that he had a twin brother. This is information he kept from someone he actually trusted. Getting personal information from him has been like pulling teeth, but he opened up to her more as his secrets were revealed and their relationship got closer.

The world is often black or white to Zero, all vampires are bad and there is nothing wrong with killing them. He says the only reason he's a Guardian is to discover the best way to kill them. Hatred is a strong word, but it's definitely the way that Zero feels about all vampires. This has caused problems recently as Yuuki's past has been uncovered and the truth of where she came from and who she is has shaken his world to the ground.

He's had trouble seeing the gray of the situation and his trust in her has shattered as trusting a pureblood is not something he'd ever believe he'd be capable of doing. In fact he's shown in recent chapters to still consider 'Vampire' Yuuki and 'Human' Yuuki as two separate entities. Even though he's finally acknowledged his feelings to her, it was purely said for that part of her before it disappeared into her vampire side. In the end, though she's done nothing wrong he still chooses to separate from her and intends on killing her.

In the past we were able to see a little of his playful side, teasing and joking occasionally with Yuuki. In recent chapters, his life has been completely destroyed again. He's lost everything that mattered to him due entirely to the manipulations of purebloods to make him into a weapon capable of killing another pureblood.

His personality has undergone a massive change because of these recent events. Most notably he previously was not a 'goal driven' person prior to this. His goals were never pursued, everything that happened to him was never because of anything he'd done. Even getting his revenge on Shizuka, she had to come to school for him to get it.

He's moving forward toward a goal for the first time in his life. Too bad it includes killing his best friend and the girl he loves...

Abilities:

It frustrates every pureblood in the series that Pureblood commands don't ever seem to touch him, even his own masters he was able to fight off. As a Vampire Hunter, he can sense and determine people with Vampiric Natures. As a Vampire, he's got most of the bonuses that come with that, plus with all of the pureblood he's ingested, he is pretty powerful. This also...made some...changes with his gun. 'Bloody Rose' has been his constant companion and decided it liked him...a little TOO much. It's become a part of him. It feeds off him and I THINK...it helps keep him sane as it drinks the blood of it's victim and gives it to Zero.

*NOTE*(this last part is just speculation from the latest chapter and from previous chapters...if this is not how it works, I will definitely modify my playing. It's a relatively new transformation for him. I --of course-- would A. need permission for keeping his gun and B. NEVER GOD MOD THIS. He wouldn't ever shoot anyone without explicit permission from the other mun...both of which are completely open for discussion at anytime. I don't bite...just Zero might.)